diff --git a/core/modules/action/src/Tests/BulkFormTest.php b/core/modules/action/src/Tests/BulkFormTest.php
index 88892c4..88c994a 100644
--- a/core/modules/action/src/Tests/BulkFormTest.php
+++ b/core/modules/action/src/Tests/BulkFormTest.php
@@ -59,7 +59,7 @@ public function testBulkForm() {
     // Make sure a checkbox appears on all rows.
     $edit = array();
     for ($i = 0; $i < 10; $i++) {
-      $this->assertFieldById('edit-node-bulk-form-' . $i, NULL, format_string('The checkbox on row @row appears.', array('@row' => $i)));
+      $this->assertFieldById('edit-node-bulk-form-' . $i, NULL, "The checkbox on row $i appears.");
       $edit["node_bulk_form[$i]"] = TRUE;
     }
 
@@ -77,7 +77,7 @@ public function testBulkForm() {
 
     foreach ($nodes as $node) {
       $changed_node = $node_storage->load($node->id());
-      $this->assertTrue($changed_node->isSticky(), format_string('Node @nid got marked as sticky.', array('@nid' => $node->id())));
+      $this->assertTrue($changed_node->isSticky(), "Node {$node->id()} got marked as sticky.");
     }
 
     $this->assertText('Make content sticky was applied to 10 items.');
diff --git a/core/modules/aggregator/src/Tests/AggregatorAdminTest.php b/core/modules/aggregator/src/Tests/AggregatorAdminTest.php
index edc594b..0a2404f 100644
--- a/core/modules/aggregator/src/Tests/AggregatorAdminTest.php
+++ b/core/modules/aggregator/src/Tests/AggregatorAdminTest.php
@@ -40,7 +40,7 @@ public function testSettingsPage() {
     $this->assertText(t('The configuration options have been saved.'));
 
     foreach ($edit as $name => $value) {
-      $this->assertFieldByName($name, $value, format_string('"@name" has correct default value.', array('@name' => $name)));
+      $this->assertFieldByName($name, $value, '"' . $name . '" has correct default value.');
     }
 
     // Check for our test processor settings form.
diff --git a/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php b/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
index 351f48c..807a5d9 100644
--- a/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
+++ b/core/modules/aggregator/src/Tests/AggregatorRenderingTest.php
@@ -60,7 +60,7 @@ public function testBlockLinks() {
     // Find the expected read_more link.
     $href = $feed->url();
     $links = $this->xpath('//a[@href = :href]', array(':href' => $href));
-    $this->assert(isset($links[0]), format_string('Link to href %href found.', array('%href' => $href)));
+    $this->assert(isset($links[0]), "Link to href $href found.");
     $cache_tags_header = $this->drupalGetHeader('X-Drupal-Cache-Tags');
     $cache_tags = explode(' ', $cache_tags_header);
     $this->assertTrue(in_array('aggregator_feed:' . $feed->id(), $cache_tags));
@@ -112,7 +112,7 @@ public function testFeedPage() {
     // Find the expected read_more link on the sources page.
     $href = $feed->url();
     $links = $this->xpath('//a[@href = :href]', array(':href' => $href));
-    $this->assertTrue(isset($links[0]), SafeMarkup::format('Link to href %href found.', array('%href' => $href)));
+    $this->assertTrue(isset($links[0]), "Link to href $href found.");
     $cache_tags_header = $this->drupalGetHeader('X-Drupal-Cache-Tags');
     $cache_tags = explode(' ', $cache_tags_header);
     $this->assertTrue(in_array('aggregator_feed:' . $feed->id(), $cache_tags));
diff --git a/core/modules/aggregator/src/Tests/FeedParserTest.php b/core/modules/aggregator/src/Tests/FeedParserTest.php
index 6da2ec8..c54b2d2 100644
--- a/core/modules/aggregator/src/Tests/FeedParserTest.php
+++ b/core/modules/aggregator/src/Tests/FeedParserTest.php
@@ -35,7 +35,7 @@ public function testRSS091Sample() {
     $feed = $this->createFeed($this->getRSS091Sample());
     $feed->refreshItems();
     $this->drupalGet('aggregator/sources/' . $feed->id());
-    $this->assertResponse(200, format_string('Feed %name exists.', array('%name' => $feed->label())));
+    $this->assertResponse(200, "Feed {$feed->label()} exists.");
     $this->assertText('First example feed item title');
     $this->assertLinkByHref('http://example.com/example-turns-one');
     $this->assertText('First example feed item description.');
@@ -58,7 +58,7 @@ public function testAtomSample() {
     $feed = $this->createFeed($this->getAtomSample());
     $feed->refreshItems();
     $this->drupalGet('aggregator/sources/' . $feed->id());
-    $this->assertResponse(200, format_string('Feed %name exists.', array('%name' => $feed->label())));
+    $this->assertResponse(200, "Feed {$feed->label()} exists.");
     $this->assertText('Atom-Powered Robots Run Amok');
     $this->assertLinkByHref('http://example.org/2003/12/13/atom03');
     $this->assertText('Some text.');
@@ -81,7 +81,7 @@ public function testHtmlEntitiesSample() {
     $feed = $this->createFeed($this->getHtmlEntitiesSample());
     $feed->refreshItems();
     $this->drupalGet('aggregator/sources/' . $feed->id());
-    $this->assertResponse(200, format_string('Feed %name exists.', array('%name' => $feed->label())));
+    $this->assertResponse(200, "Feed {$feed->label()} exists.");
     $this->assertRaw("Quote&quot; Amp&amp;");
   }
 
diff --git a/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php b/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
index 0e94425..a345d26 100644
--- a/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
+++ b/core/modules/aggregator/src/Tests/UpdateFeedItemTest.php
@@ -37,10 +37,10 @@ public function testUpdateFeedItem() {
     );
 
     $this->drupalGet($edit['url[0][value]']);
-    $this->assertResponse(array(200), format_string('URL !url is accessible', array('!url' => $edit['url[0][value]'])));
+    $this->assertResponse(array(200), "URL {$edit['url[0][value]']} is accessible");
 
     $this->drupalPostForm('aggregator/sources/add', $edit, t('Save'));
-    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), format_string('The feed !name has been added.', array('!name' => $edit['title[0][value]'])));
+    $this->assertRaw(t('The feed %name has been added.', array('%name' => $edit['title[0][value]'])), "The feed {$edit['title[0][value]']} has been added.");
 
     $fid = db_query("SELECT fid FROM {aggregator_feed} WHERE url = :url", array(':url' => $edit['url[0][value]']))->fetchField();
     $feed = Feed::load($fid);
@@ -62,7 +62,7 @@ public function testUpdateFeedItem() {
     $feed->refreshItems();
 
     $after = db_query('SELECT timestamp FROM {aggregator_item} WHERE fid = :fid', array(':fid' => $feed->id()))->fetchField();
-    $this->assertTrue($before === $after, format_string('Publish timestamp of feed item was not updated (!before === !after)', array('!before' => $before, '!after' => $after)));
+    $this->assertTrue($before === $after, "Publish timestamp of feed item was not updated ($before === $after)");
 
     // Make sure updating items works even after uninstalling a module
     // that provides the selected plugins.
diff --git a/core/modules/aggregator/src/Tests/UpdateFeedTest.php b/core/modules/aggregator/src/Tests/UpdateFeedTest.php
index c660756..019d938 100644
--- a/core/modules/aggregator/src/Tests/UpdateFeedTest.php
+++ b/core/modules/aggregator/src/Tests/UpdateFeedTest.php
@@ -29,7 +29,7 @@ public function testUpdateFeed() {
         $edit[$same_field] = $feed->{$same_field}->value;
       }
       $this->drupalPostForm('aggregator/sources/' . $feed->id() . '/configure', $edit, t('Save'));
-      $this->assertRaw(t('The feed %name has been updated.', array('%name' => $edit['title[0][value]'])), format_string('The feed %name has been updated.', array('%name' => $edit['title[0][value]'])));
+      $this->assertRaw(t('The feed %name has been updated.', array('%name' => $edit['title[0][value]'])), "The feed {$edit['title[0][value]']} has been updated.");
 
       // Check feed data.
       $this->assertUrl($feed->url('canonical', ['absolute' => TRUE]));
diff --git a/core/modules/basic_auth/src/Tests/Authentication/BasicAuthTest.php b/core/modules/basic_auth/src/Tests/Authentication/BasicAuthTest.php
index e548552..4f77ec5 100644
--- a/core/modules/basic_auth/src/Tests/Authentication/BasicAuthTest.php
+++ b/core/modules/basic_auth/src/Tests/Authentication/BasicAuthTest.php
@@ -54,7 +54,7 @@ public function testBasicAuth() {
     $this->curlClose();
 
     $this->drupalGet($url);
-    $this->assertEqual($this->drupalGetHeader('WWW-Authenticate'), SafeMarkup::format('Basic realm="@realm"', ['@realm' => \Drupal::config('system.site')->get('name')]));
+    $this->assertEqual($this->drupalGetHeader('WWW-Authenticate'), 'Basic realm="' . \Drupal::config('system.site')->get('name') . '"');
     $this->assertResponse('401', 'Not authenticated on the route that allows only basic_auth. Prompt to authenticate received.');
 
     $this->drupalGet('admin');
diff --git a/core/modules/block/src/Tests/BlockTest.php b/core/modules/block/src/Tests/BlockTest.php
index 17fd982..e97f76c 100644
--- a/core/modules/block/src/Tests/BlockTest.php
+++ b/core/modules/block/src/Tests/BlockTest.php
@@ -286,7 +286,7 @@ function moveBlockToRegion(array $block, $region) {
     $this->drupalPostForm('admin/structure/block', $edit, t('Save blocks'));
 
     // Confirm that the block was moved to the proper region.
-    $this->assertText(t('The block settings have been updated.'), format_string('Block successfully moved to %region_name region.', array( '%region_name' => $region)));
+    $this->assertText(t('The block settings have been updated.'), "Block successfully moved to $region region.");
 
     // Confirm that the block is being displayed.
     $this->drupalGet('');
diff --git a/core/modules/block/src/Tests/Views/DisplayBlockTest.php b/core/modules/block/src/Tests/Views/DisplayBlockTest.php
index 880f68c..24799bf 100644
--- a/core/modules/block/src/Tests/Views/DisplayBlockTest.php
+++ b/core/modules/block/src/Tests/Views/DisplayBlockTest.php
@@ -273,8 +273,8 @@ public function testBlockContextualLinks() {
     $id = 'block:block=' . $block->id() . ':langcode=en|entity.view.edit_form:view=test_view_block:location=block&name=test_view_block&display_id=block_1&langcode=en';
     $cached_id = 'block:block=' . $cached_block->id() . ':langcode=en|entity.view.edit_form:view=test_view_block:location=block&name=test_view_block&display_id=block_1&langcode=en';
     // @see \Drupal\contextual\Tests\ContextualDynamicContextTest:assertContextualLinkPlaceHolder()
-    $this->assertRaw('<div' . new Attribute(array('data-contextual-id' => $id)) . '></div>', format_string('Contextual link placeholder with id @id exists.', array('@id' => $id)));
-    $this->assertRaw('<div' . new Attribute(array('data-contextual-id' => $cached_id)) . '></div>', format_string('Contextual link placeholder with id @id exists.', array('@id' => $cached_id)));
+    $this->assertRaw('<div' . new Attribute(array('data-contextual-id' => $id)) . '></div>', "Contextual link placeholder with id $id exists.");
+    $this->assertRaw('<div' . new Attribute(array('data-contextual-id' => $cached_id)) . '></div>', "Contextual link placeholder with id $cached_id exists.");
 
     // Get server-rendered contextual links.
     // @see \Drupal\contextual\Tests\ContextualDynamicContextTest:renderContextualLinks()
diff --git a/core/modules/block_content/src/Tests/BlockContentCreationTest.php b/core/modules/block_content/src/Tests/BlockContentCreationTest.php
index 6bf250c..0a75b4f 100644
--- a/core/modules/block_content/src/Tests/BlockContentCreationTest.php
+++ b/core/modules/block_content/src/Tests/BlockContentCreationTest.php
@@ -48,10 +48,7 @@ public function testBlockContentCreation() {
     $this->drupalPostForm('block/add/basic', $edit, t('Save'));
 
     // Check that the Basic block has been created.
-    $this->assertRaw(format_string('!block %name has been created.', array(
-      '!block' => 'basic',
-      '%name' => $edit['info[0][value]']
-    )), 'Basic block created.');
+    $this->assertRaw('basic <em class="placeholder">' . $edit['info[0][value]'] . '</em> has been created.', 'Basic block created.');
 
     // Check that the view mode setting is hidden because only one exists.
     $this->assertNoFieldByXPath('//select[@name="settings[view_mode]"]', NULL, 'View mode setting hidden because only one exists');
@@ -66,9 +63,7 @@ public function testBlockContentCreation() {
     $this->drupalPostForm('block/add/basic', $edit, t('Save'));
 
     // Check that the Basic block has been created.
-    $this->assertRaw(format_string('A block with description %name already exists.', array(
-      '%name' => $edit['info[0][value]']
-    )));
+    $this->assertRaw('A block with description <em class="placeholder">' . $edit['info[0][value]'] .'</em> already exists.');
     $this->assertResponse(200);
   }
 
@@ -95,10 +90,7 @@ public function testBlockContentCreationMultipleViewModes() {
     $this->drupalPostForm('block/add/basic', $edit, t('Save'));
 
     // Check that the Basic block has been created.
-    $this->assertRaw(format_string('!block %name has been created.', array(
-      '!block' => 'basic',
-      '%name' => $edit['info[0][value]']
-    )), 'Basic block created.');
+    $this->assertRaw('basic <em class="placeholder">' . $edit['info[0][value]'] . '</em> has been created.', 'Basic block created.');
 
     // Check that the view mode setting is shown because more than one exists.
     $this->assertFieldByXPath('//select[@name="settings[view_mode]"]', NULL, 'View mode setting shown because multiple exist');
@@ -124,9 +116,7 @@ public function testBlockContentCreationMultipleViewModes() {
     $this->drupalPostForm('block/add/basic', $edit, t('Save'));
 
     // Check that the Basic block has been created.
-    $this->assertRaw(format_string('A block with description %name already exists.', array(
-      '%name' => $edit['info[0][value]']
-    )));
+    $this->assertRaw('A block with description <em class="placeholder">' . $edit['info[0][value]'] .'</em> already exists.');
     $this->assertResponse(200);
   }
 
@@ -144,10 +134,7 @@ public function testDefaultBlockContentCreation() {
     $this->drupalPostForm('block/add', $edit, t('Save'));
 
     // Check that the block has been created and that it is a basic block.
-    $this->assertRaw(format_string('!block %name has been created.', array(
-      '!block' => 'basic',
-      '%name' => $edit['info[0][value]'],
-    )), 'Basic block created.');
+    $this->assertRaw('basic <em class="placeholder">' . $edit['info[0][value]'] . '</em> has been created.', 'Basic block created.');
 
     // Check that the block exists in the database.
     $blocks = entity_load_multiple_by_properties('block_content', array('info' => $edit['info[0][value]']));
diff --git a/core/modules/block_content/src/Tests/BlockContentRevisionsTest.php b/core/modules/block_content/src/Tests/BlockContentRevisionsTest.php
index 8da9c54..405263f 100644
--- a/core/modules/block_content/src/Tests/BlockContentRevisionsTest.php
+++ b/core/modules/block_content/src/Tests/BlockContentRevisionsTest.php
@@ -69,9 +69,7 @@ public function testRevisions() {
       // Confirm the correct revision text appears.
       $loaded = entity_revision_load('block_content', $revision_id);
       // Verify revision log is the same.
-      $this->assertEqual($loaded->getRevisionLog(), $logs[$delta], format_string('Correct log message found for revision !revision', array(
-        '!revision' => $loaded->getRevisionId(),
-      )));
+      $this->assertEqual($loaded->getRevisionLog(), "Correct log message found for revision {$loaded->getRevisionId()}");
     }
 
     // Confirm that this is the default revision.
diff --git a/core/modules/block_content/src/Tests/BlockContentValidationTest.php b/core/modules/block_content/src/Tests/BlockContentValidationTest.php
index 262d8d0..f983ac2 100644
--- a/core/modules/block_content/src/Tests/BlockContentValidationTest.php
+++ b/core/modules/block_content/src/Tests/BlockContentValidationTest.php
@@ -37,9 +37,7 @@ public function testValidation() {
     // Make sure the violation is on the info property
     $this->assertEqual($violations[0]->getPropertyPath(), 'info');
     // Make sure the message is correct.
-    $this->assertEqual($violations[0]->getMessage(), format_string('A block with description %value already exists.', [
-      '%value' => $block->label(),
-    ]));
+    $this->assertEqual($violations[0]->getMessage(), "A block with description {$block->label()} already exists.");
   }
 
 }
diff --git a/core/modules/block_content/src/Tests/PageEditTest.php b/core/modules/block_content/src/Tests/PageEditTest.php
index fdd1743..881c0e3 100644
--- a/core/modules/block_content/src/Tests/PageEditTest.php
+++ b/core/modules/block_content/src/Tests/PageEditTest.php
@@ -64,7 +64,7 @@ public function testPageEdit() {
     // Test deleting the block.
     $this->drupalGet("block/" . $revised_block->id());
     $this->clickLink(t('Delete'));
-    $this->assertText(format_string('Are you sure you want to delete the custom block !label?', array('!label' => $revised_block->label())));
+    $this->assertText("Are you sure you want to delete the custom block {$revised_block->label()}?");
   }
 
 }
diff --git a/core/modules/book/src/Tests/BookTest.php b/core/modules/book/src/Tests/BookTest.php
index b0235c4..503e6fc 100644
--- a/core/modules/book/src/Tests/BookTest.php
+++ b/core/modules/book/src/Tests/BookTest.php
@@ -255,10 +255,10 @@ function checkBookNode(EntityInterface $node, $nodes, $previous = FALSE, $up = F
 
     // Check outline structure.
     if ($nodes !== NULL) {
-      $this->assertPattern($this->generateOutlinePattern($nodes), format_string('Node @number outline confirmed.', array('@number' => $number)));
+      $this->assertPattern($this->generateOutlinePattern($nodes), "Node $number outline confirmed.");
     }
     else {
-      $this->pass(format_string('Node %number does not have outline.', array('%number' => $number)));
+      $this->pass("Node $number does not have outline.");
     }
 
     // Check previous, up, and next links.
@@ -266,7 +266,7 @@ function checkBookNode(EntityInterface $node, $nodes, $previous = FALSE, $up = F
       /** @var \Drupal\Core\Url $url */
       $url = $previous->urlInfo();
       $url->setOptions(array('attributes' => array('rel' => array('prev'), 'title' => t('Go to previous page'))));
-      $text = SafeMarkup::format('<b>‹</b> @label', array('@label' => $previous->label()));
+      $text = "<b>‹</b> {$previous->label()}";
       $this->assertRaw(\Drupal::l($text, $url), 'Previous page link found.');
     }
 
@@ -281,7 +281,7 @@ function checkBookNode(EntityInterface $node, $nodes, $previous = FALSE, $up = F
       /** @var \Drupal\Core\Url $url */
       $url = $next->urlInfo();
       $url->setOptions(array('attributes' => array('rel' => array('next'), 'title' => t('Go to next page'))));
-      $text = SafeMarkup::format('@label <b>›</b>', array('@label' => $next->label()));
+      $text = "$next->label() <b>›</b>";
       $this->assertRaw(\Drupal::l($text, $url), 'Next page link found.');
     }
 
@@ -431,7 +431,7 @@ function testBookNavigationBlock() {
     $nodes = $this->createBook();
     $this->drupalGet('<front>');
     $this->assertText($block->label(), 'Book navigation block is displayed.');
-    $this->assertText($this->book->label(), format_string('Link to book root (@title) is displayed.', array('@title' => $nodes[0]->label())));
+    $this->assertText($this->book->label(), "Link to book root ({$nodes[0]->label()}) is displayed.");
     $this->assertNoText($nodes[0]->label(), 'No links to individual book pages are displayed.');
   }
 
diff --git a/core/modules/comment/src/Tests/CommentFieldAccessTest.php b/core/modules/comment/src/Tests/CommentFieldAccessTest.php
index ba1c0d3..a1c4852 100644
--- a/core/modules/comment/src/Tests/CommentFieldAccessTest.php
+++ b/core/modules/comment/src/Tests/CommentFieldAccessTest.php
@@ -213,29 +213,21 @@ public function testAccessToAdministrativeFields() {
       foreach ($permutations as $set) {
         $may_view = $set['comment']->{$field}->access('view', $set['user']);
         $may_update = $set['comment']->{$field}->access('edit', $set['user']);
-        $this->assertEqual($may_view, $set['user']->hasPermission('administer comments') || ($set['comment']->isPublished() && $set['user']->hasPermission('access comments')), SafeMarkup::format('User @user !state view field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_update ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
-        $this->assertEqual($may_update, $set['user']->hasPermission('administer comments'), SafeMarkup::format('User @user !state update field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_update ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
+        $username = $set['user']->getUsername();
+        $state = $may_update ? 'can' : 'cannot';
+        $comment_subject = $set['comment']->getSubject();
+        $this->assertEqual($may_view, $set['user']->hasPermission('administer comments') || ($set['comment']->isPublished() && $set['user']->hasPermission('access comments')), "User $username $state view field $field on comment $comment_subject");
+        $this->assertEqual($may_update, $set['user']->hasPermission('administer comments'), "User $username $state update field $field on comment $comment_subject");
       }
     }
 
     // Check access to normal field.
     foreach ($permutations as $set) {
+      $username = $set['user']->getUsername();
+      $state = $may_update ? 'can' : 'cannot';
+      $comment_subject = $set['comment']->getSubject();
       $may_update = $set['comment']->access('update', $set['user']) && $set['comment']->subject->access('edit', $set['user']);
-      $this->assertEqual($may_update, $set['user']->hasPermission('administer comments') || ($set['user']->hasPermission('edit own comments') && $set['user']->id() == $set['comment']->getOwnerId()), SafeMarkup::format('User @user !state update field subject on comment @comment', [
-        '@user' => $set['user']->getUsername(),
-        '!state' => $may_update ? 'can' : 'cannot',
-        '@comment' => $set['comment']->getSubject(),
-      ]));
+      $this->assertEqual($may_update, $set['user']->hasPermission('administer comments') || ($set['user']->hasPermission('edit own comments') && $set['user']->id() == $set['comment']->getOwnerId()), "User $username $state update field subject on comment $comment_subject");
     }
 
     // Check read-only fields.
@@ -244,19 +236,12 @@ public function testAccessToAdministrativeFields() {
       foreach ($permutations as $set) {
         $may_view = $set['comment']->{$field}->access('view', $set['user']);
         $may_update = $set['comment']->{$field}->access('edit', $set['user']);
+        $username = $set['user']->getUsername();
+        $state = $may_update ? 'can' : 'cannot';
+        $comment_subject = $set['comment']->getSubject();
         $this->assertEqual($may_view, $field != 'hostname' && ($set['user']->hasPermission('administer comments') ||
-            ($set['comment']->isPublished() && $set['user']->hasPermission('access comments'))), SafeMarkup::format('User @user !state view field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_view ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
-        $this->assertFalse($may_update, SafeMarkup::format('User @user !state update field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_update ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
+            ($set['comment']->isPublished() && $set['user']->hasPermission('access comments'))), "User $username $state view field $field on comment $comment_subject");
+        $this->assertFalse($may_update, "User $username $state update field $field on comment $comment_subject");
       }
     }
 
@@ -266,19 +251,12 @@ public function testAccessToAdministrativeFields() {
       foreach ($permutations as $set) {
         $may_view = $set['comment']->{$field}->access('view', $set['user']);
         $may_update = $set['comment']->{$field}->access('edit', $set['user']);
+        $username = $set['user']->getUsername();
+        $state = $may_update ? 'can' : 'cannot';
+        $comment_subject = $set['comment']->getSubject();
         $this->assertEqual($may_view, $field != 'hostname' && ($set['user']->hasPermission('administer comments') ||
-            ($set['comment']->isPublished() && $set['user']->hasPermission('access comments'))), SafeMarkup::format('User @user !state view field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_view ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
-        $this->assertEqual($may_update, $set['user']->hasPermission('post comments') && $set['comment']->isNew(), SafeMarkup::format('User @user !state update field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_update ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
+            ($set['comment']->isPublished() && $set['user']->hasPermission('access comments'))), "User $username $state view field $field on comment $comment_subject");
+        $this->assertEqual($may_update, $set['user']->hasPermission('post comments') && $set['comment']->isNew(), "User $username $state update field $field on comment $comment_subject");
       }
     }
 
@@ -287,6 +265,9 @@ public function testAccessToAdministrativeFields() {
       // Check view operation.
       foreach ($permutations as $set) {
         $may_update = $set['comment']->{$field}->access('edit', $set['user']);
+        $username = $set['user']->getUsername();
+        $state = $may_update ? 'can' : 'cannot';
+        $comment_subject = $set['comment']->getSubject();
         // To edit the 'mail' or 'name' field, either the user has the
         // "administer comments" permissions or the user is anonymous and
         // adding a new comment using a field that allows contact details.
@@ -295,12 +276,7 @@ public function testAccessToAdministrativeFields() {
             $set['comment']->isNew() &&
             $set['user']->hasPermission('post comments') &&
             $set['comment']->getFieldName() == 'comment_other'
-          ), SafeMarkup::format('User @user !state update field !field on comment @comment', [
-          '@user' => $set['user']->getUsername(),
-          '!state' => $may_update ? 'can' : 'cannot',
-          '@comment' => $set['comment']->getSubject(),
-          '!field' => $field,
-        ]));
+          ), "User $username $state update field $field on comment $comment_subject.");
       }
     }
     foreach ($permutations as $set) {
diff --git a/core/modules/comment/src/Tests/CommentFieldsTest.php b/core/modules/comment/src/Tests/CommentFieldsTest.php
index ede2e91..170dc7d 100644
--- a/core/modules/comment/src/Tests/CommentFieldsTest.php
+++ b/core/modules/comment/src/Tests/CommentFieldsTest.php
@@ -56,7 +56,7 @@ function testCommentDefaultFields() {
     $field_storage = FieldStorageConfig::loadByName('comment', 'comment_body');
     $this->assertTrue($field_storage, 'The comment_body field exists');
     $field = FieldConfig::loadByName('comment', 'comment', 'comment_body');
-    $this->assertTrue(isset($field), format_string('The comment_body field is present for comments on type @type', array('@type' => $type_name)));
+    $this->assertTrue(isset($field), "The comment_body field is present for comments on type $type_name");
 
     // Test adding a field that defaults to CommentItemInterface::CLOSED.
     $this->addDefaultCommentField('node', 'test_node_type', 'who_likes_ponies', CommentItemInterface::CLOSED, 'who_likes_ponies');
diff --git a/core/modules/comment/src/Tests/CommentLanguageTest.php b/core/modules/comment/src/Tests/CommentLanguageTest.php
index 8db195d..90e05f5 100644
--- a/core/modules/comment/src/Tests/CommentLanguageTest.php
+++ b/core/modules/comment/src/Tests/CommentLanguageTest.php
@@ -122,8 +122,7 @@ function testCommentLanguage() {
           ->range(0, 1)
           ->execute();
         $comment = Comment::load(reset($cids));
-        $args = array('%node_language' => $node_langcode, '%comment_language' => $comment->langcode->value, '%langcode' => $langcode);
-        $this->assertEqual($comment->langcode->value, $langcode, format_string('The comment posted with content language %langcode and belonging to the node with language %node_language has language %comment_language', $args));
+        $this->assertEqual($comment->langcode->value, $langcode, "The comment posted with content language $langcode and belonging to the node with language $node_langcode has language {$comment->langcode->value}");
         $this->assertEqual($comment->comment_body->value, $comment_values[$node_langcode][$langcode], 'Comment body correctly stored.');
       }
     }
diff --git a/core/modules/comment/src/Tests/CommentNonNodeTest.php b/core/modules/comment/src/Tests/CommentNonNodeTest.php
index 8d8e38b..25269ba 100644
--- a/core/modules/comment/src/Tests/CommentNonNodeTest.php
+++ b/core/modules/comment/src/Tests/CommentNonNodeTest.php
@@ -226,10 +226,10 @@ function performCommentOperation($comment, $operation, $approval = FALSE) {
 
     if ($operation == 'delete') {
       $this->drupalPostForm(NULL, array(), t('Delete comments'));
-      $this->assertRaw(\Drupal::translation()->formatPlural(1, 'Deleted 1 comment.', 'Deleted @count comments.'), format_string('Operation "@operation" was performed on comment.', array('@operation' => $operation)));
+      $this->assertRaw(\Drupal::translation()->formatPlural(1, 'Deleted 1 comment.', 'Deleted @count comments.'), 'Operation "' . $operation . '" was performed on comment.');
     }
     else {
-      $this->assertText(t('The update has been performed.'), format_string('Operation "@operation" was performed on comment.', array('@operation' => $operation)));
+      $this->assertText(t('The update has been performed.'), 'Operation "' . $operation . '" was performed on comment.');
     }
   }
 
diff --git a/core/modules/comment/src/Tests/CommentPagerTest.php b/core/modules/comment/src/Tests/CommentPagerTest.php
index 92fc9ff..f0b6b52 100644
--- a/core/modules/comment/src/Tests/CommentPagerTest.php
+++ b/core/modules/comment/src/Tests/CommentPagerTest.php
@@ -191,7 +191,7 @@ function assertCommentOrder(array $comments, array $expected_order) {
     foreach ($comment_anchors as $anchor) {
       $result_order[] = substr($anchor['id'], 8);
     }
-    return $this->assertEqual($expected_cids, $result_order, format_string('Comment order: expected @expected, returned @returned.', array('@expected' => implode(',', $expected_cids), '@returned' => implode(',', $result_order))));
+    return $this->assertEqual($expected_cids, $result_order, 'Comment order: expected ' . implode(',', $expected_cids) . ', returned ' . implode(',', $result_order) . '.');
   }
 
   /**
@@ -251,7 +251,7 @@ function testCommentNewPageIndicator() {
     foreach ($expected_pages as $new_replies => $expected_page) {
       $returned_page = \Drupal::entityManager()->getStorage('comment')
         ->getNewCommentPageNumber($node->get('comment')->comment_count, $new_replies, $node);
-      $this->assertIdentical($expected_page, $returned_page, format_string('Flat mode, @new replies: expected page @expected, returned page @returned.', array('@new' => $new_replies, '@expected' => $expected_page, '@returned' => $returned_page)));
+      $this->assertIdentical($expected_page, $returned_page, "Flat mode, $new_replies replies: expected page $expected_page, returned page $returned_page.");
     }
 
     $this->setCommentSettings('default_mode', CommentManagerInterface::COMMENT_MODE_THREADED, 'Switched to threaded mode.');
@@ -270,7 +270,7 @@ function testCommentNewPageIndicator() {
     foreach ($expected_pages as $new_replies => $expected_page) {
       $returned_page = \Drupal::entityManager()->getStorage('comment')
         ->getNewCommentPageNumber($node->get('comment')->comment_count, $new_replies, $node);
-      $this->assertEqual($expected_page, $returned_page, format_string('Threaded mode, @new replies: expected page @expected, returned page @returned.', array('@new' => $new_replies, '@expected' => $expected_page, '@returned' => $returned_page)));
+      $this->assertEqual($expected_page, $returned_page, "Threaded mode, $new_replies replies: expected page $expected_page, returned page $returned_page.");
     }
   }
 
@@ -382,10 +382,10 @@ protected function clickLinkWithXPath($xpath, $arguments = array(), $index = 0)
     $urls = $this->xpath($xpath, $arguments);
     if (isset($urls[$index])) {
       $url_target = $this->getAbsoluteUrl($urls[$index]['href']);
-      $this->pass(SafeMarkup::format('Clicked link %label (@url_target) from @url_before', array('%label' => $xpath, '@url_target' => $url_target, '@url_before' => $url_before)), 'Browser');
+      $this->pass("Clicked link $xpath ($url_target) from $url_before", 'Browser');
       return $this->drupalGet($url_target);
     }
-    $this->fail(SafeMarkup::format('Link %label does not exist on @url_before', array('%label' => $xpath, '@url_before' => $url_before)), 'Browser');
+    $this->fail("Link $xpath does not exist on $url_before", 'Browser');
     return FALSE;
   }
 
diff --git a/core/modules/comment/src/Tests/CommentThreadingTest.php b/core/modules/comment/src/Tests/CommentThreadingTest.php
index 14db3cc..8c5bde5 100644
--- a/core/modules/comment/src/Tests/CommentThreadingTest.php
+++ b/core/modules/comment/src/Tests/CommentThreadingTest.php
@@ -142,13 +142,7 @@ protected function assertParentLink($cid, $pid) {
     //  </article>
     $pattern = "//a[@id='comment-$cid']/following-sibling::article//p[contains(@class, 'parent')]//a[contains(@href, 'comment-$pid')]";
 
-    $this->assertFieldByXpath($pattern, NULL, format_string(
-      'Comment %cid has a link to parent %pid.',
-      array(
-        '%cid' => $cid,
-        '%pid' => $pid,
-      )
-    ));
+    $this->assertFieldByXpath($pattern, NULL, "Comment $cid has a link to parent $pid.");
   }
 
   /**
@@ -165,12 +159,7 @@ protected function assertNoParentLink($cid) {
     //  </article>
 
     $pattern = "//a[@id='comment-$cid']/following-sibling::article//p[contains(@class, 'parent')]";
-    $this->assertNoFieldByXpath($pattern, NULL, format_string(
-      'Comment %cid does not have a link to a parent.',
-      array(
-        '%cid' => $cid,
-      )
-    ));
+    $this->assertNoFieldByXpath($pattern, NULL, "Comment $cid does not have a link to a parent.");
   }
 
 }
diff --git a/core/modules/comment/src/Tests/CommentTokenReplaceTest.php b/core/modules/comment/src/Tests/CommentTokenReplaceTest.php
index c1f4303..cacf04f 100644
--- a/core/modules/comment/src/Tests/CommentTokenReplaceTest.php
+++ b/core/modules/comment/src/Tests/CommentTokenReplaceTest.php
@@ -113,7 +113,7 @@ function testCommentTokenReplacement() {
     foreach ($tests as $input => $expected) {
       $bubbleable_metadata = new BubbleableMetadata();
       $output = $token_service->replace($input, array('comment' => $comment), array('langcode' => $language_interface->getId()), $bubbleable_metadata);
-      $this->assertEqual($output, $expected, format_string('Sanitized comment token %token replaced.', array('%token' => $input)));
+      $this->assertEqual($output, $expected, "Sanitized comment token $input replaced.");
       $this->assertEqual($bubbleable_metadata, $metadata_tests[$input]);
     }
 
@@ -131,7 +131,7 @@ function testCommentTokenReplacement() {
 
     foreach ($tests as $input => $expected) {
       $output = $token_service->replace($input, array('comment' => $comment), array('langcode' => $language_interface->getId(), 'sanitize' => FALSE));
-      $this->assertEqual($output, $expected, format_string('Unsanitized comment token %token replaced.', array('%token' => $input)));
+      $this->assertEqual($output, $expected, "Unsanitized comment token $input replaced.");
     }
 
     // Test anonymous comment author.
@@ -139,9 +139,9 @@ function testCommentTokenReplacement() {
     $comment->setOwnerId(0)->setAuthorName($author_name);
     $input = '[comment:author]';
     $output = $token_service->replace($input, array('comment' => $comment), array('langcode' => $language_interface->getId()));
-    $this->assertEqual($output, Xss::filter($author_name), format_string('Sanitized comment author token %token replaced.', array('%token' => $input)));
+    $this->assertEqual($output, Xss::filter($author_name), "Sanitized comment author token $input replaced.");
     $output = $token_service->replace($input, array('comment' => $comment), array('langcode' => $language_interface->getId(), 'sanitize' => FALSE));
-    $this->assertEqual($output, $author_name, format_string('Unsanitized comment author token %token replaced.', array('%token' => $input)));
+    $this->assertEqual($output, $author_name, "Unsanitized comment author token $input replaced.");
 
     // Load node so comment_count gets computed.
     $node = Node::load($node->id());
@@ -153,7 +153,7 @@ function testCommentTokenReplacement() {
 
     foreach ($tests as $input => $expected) {
       $output = $token_service->replace($input, array('entity' => $node, 'node' => $node), array('langcode' => $language_interface->getId()));
-      $this->assertEqual($output, $expected, format_string('Node comment token %token replaced.', array('%token' => $input)));
+      $this->assertEqual($output, $expected, "Node comment token $input replaced.");
     }
   }
 
diff --git a/core/modules/comment/src/Tests/Views/DefaultViewRecentCommentsTest.php b/core/modules/comment/src/Tests/Views/DefaultViewRecentCommentsTest.php
index 89b03b3..27ce903 100644
--- a/core/modules/comment/src/Tests/Views/DefaultViewRecentCommentsTest.php
+++ b/core/modules/comment/src/Tests/Views/DefaultViewRecentCommentsTest.php
@@ -135,11 +135,7 @@ public function testBlockDisplay() {
     $this->assertIdenticalResultset($view, $expected_result, $map);
 
     // Check the number of results given by the display is the expected.
-    $this->assertEqual(sizeof($view->result), $this->blockDisplayResults,
-      format_string('There are exactly @results comments. Expected @expected',
-        array('@results' => count($view->result), '@expected' => $this->blockDisplayResults)
-      )
-    );
+    $this->assertEqual(sizeof($view->result), $this->blockDisplayResults, 'There are exactly ' . count($view->result) . ' comments. Expected ' . $this->blockDisplayResults . '.');
   }
 
 }
diff --git a/core/modules/config/src/Tests/ConfigCRUDTest.php b/core/modules/config/src/Tests/ConfigCRUDTest.php
index 70b8919..85d39df 100644
--- a/core/modules/config/src/Tests/ConfigCRUDTest.php
+++ b/core/modules/config/src/Tests/ConfigCRUDTest.php
@@ -191,9 +191,7 @@ function testNameValidation() {
         unset($test_characters[$i]);
       }
     }
-    $this->assertTrue(empty($test_characters), format_string('Expected ConfigNameException was thrown for all invalid name characters: @characters', array(
-      '@characters' => implode(' ', $characters),
-    )));
+    $this->assertTrue(empty($test_characters), 'Expected ConfigNameException was thrown for all invalid name characters: ' . implode(' ', $characters));
 
     // Verify that a valid config object name can be saved.
     $name = 'namespace.object';
diff --git a/core/modules/config/src/Tests/ConfigDiffTest.php b/core/modules/config/src/Tests/ConfigDiffTest.php
index 10f6902..6596a7c 100644
--- a/core/modules/config/src/Tests/ConfigDiffTest.php
+++ b/core/modules/config/src/Tests/ConfigDiffTest.php
@@ -53,8 +53,8 @@ function testDiff() {
     $diff = \Drupal::service('config.manager')->diff($active, $staging, $config_name);
     $edits = $diff->getEdits();
     $this->assertEqual($edits[0]->type, 'change', 'The first item in the diff is a change.');
-    $this->assertEqual($edits[0]->orig[0], $change_key . ': ' . $original_data[$change_key], format_string("The active value for key '%change_key' is '%original_data'.", array('%change_key' => $change_key, '%original_data' => $original_data[$change_key])));
-    $this->assertEqual($edits[0]->closing[0], $change_key . ': ' . $change_data, format_string("The staging value for key '%change_key' is '%change_data'.", array('%change_key' => $change_key, '%change_data' => $change_data)));
+    $this->assertEqual($edits[0]->orig[0], $change_key . ': ' . $original_data[$change_key], "The active value for key '$change_key' is '$original_data[$change_key]'.");
+    $this->assertEqual($edits[0]->closing[0], $change_key . ': ' . $change_data, "The staging value for key '$change_key' is '$change_data'.");
 
     // Reset data back to original, and remove a key
     $staging_data = $original_data;
@@ -66,8 +66,8 @@ function testDiff() {
     $edits = $diff->getEdits();
     $this->assertEqual($edits[0]->type, 'copy', 'The first item in the diff is a copy.');
     $this->assertEqual($edits[1]->type, 'delete', 'The second item in the diff is a delete.');
-    $this->assertEqual($edits[1]->orig[0], $remove_key . ': ' . $original_data[$remove_key], format_string("The active value for key '%remove_key' is '%original_data'.", array('%remove_key' => $remove_key, '%original_data' => $original_data[$remove_key])));
-    $this->assertFalse($edits[1]->closing, format_string("The key '%remove_key' does not exist in staging.", array('%remove_key' => $remove_key)));
+    $this->assertEqual($edits[1]->orig[0], $remove_key . ': ' . $original_data[$remove_key], "The active value for key '$remove_key' is '$original_data[$remove_key]'.");
+    $this->assertFalse($edits[1]->closing, "The key '$remove_key' does not exist in staging.");
 
     // Reset data back to original and add a key
     $staging_data = $original_data;
@@ -79,8 +79,8 @@ function testDiff() {
     $edits = $diff->getEdits();
     $this->assertEqual($edits[0]->type, 'copy', 'The first item in the diff is a copy.');
     $this->assertEqual($edits[1]->type, 'add', 'The second item in the diff is an add.');
-    $this->assertFalse($edits[1]->orig, format_string("The key '%add_key' does not exist in active.", array('%add_key' => $add_key)));
-    $this->assertEqual($edits[1]->closing[0], $add_key . ': ' . $add_data, format_string("The staging value for key '%add_key' is '%add_data'.", array('%add_key' => $add_key, '%add_data' => $add_data)));
+    $this->assertFalse($edits[1]->orig, "The key '$add_key' does not exist in active.");
+    $this->assertEqual($edits[1]->closing[0], $add_key . ': ' . $add_data, "The staging value for key '$add_key' is '$add_data'.");
 
     // Test diffing a renamed config entity.
     $test_entity_id = $this->randomMachineName();
diff --git a/core/modules/config/src/Tests/ConfigImportUITest.php b/core/modules/config/src/Tests/ConfigImportUITest.php
index dd00edf..9837f42 100644
--- a/core/modules/config/src/Tests/ConfigImportUITest.php
+++ b/core/modules/config/src/Tests/ConfigImportUITest.php
@@ -290,7 +290,7 @@ function testImportDiff() {
 
     // Load the diff UI and verify that the diff reflects the change.
     $this->drupalGet('admin/config/development/configuration/sync/diff/' . $config_name);
-    $this->assertTitle(format_string('View changes of @config_name | Drupal', array('@config_name' => $config_name)));
+    $this->assertTitle("View changes of $config_name | Drupal");
 
     // Reset data back to original, and remove a key
     $staging_data = $original_data;
@@ -403,7 +403,7 @@ function testImportErrorLog() {
 
     // Attempt to import configuration and verify that an error message appears.
     $this->drupalPostForm(NULL, array(), t('Import all'));
-    $this->assertText(SafeMarkup::format('Deleted and replaced configuration entity "@name"', array('@name' => $name_secondary)));
+    $this->assertText('Deleted and replaced configuration entity "' . @$name_secondary . '"');
     $this->assertText(t('The configuration was imported with errors.'));
     $this->assertNoText(t('The configuration was imported successfully.'));
     $this->assertText(t('There are no configuration changes to import.'));
@@ -423,11 +423,11 @@ public function testEntityBundleDelete() {
     $this->drupalGet('admin/config/development/configuration');
     // The node type, body field and entity displays will be scheduled for
     // removal.
-    $this->assertText(format_string('node.type.@type', array('@type' => $node_type->id())));
-    $this->assertText(format_string('field.field.node.@type.body', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_view_display.node.@type.teaser', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_view_display.node.@type.default', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_form_display.node.@type.default', array('@type' => $node_type->id())));
+    $this->assertText("node.type.{$node_type->id()}");
+    $this->assertText("field.field.node.{$node_type->id()}.body");
+    $this->assertText("core.entity_view_display.node.{$node_type->id()}.teaser");
+    $this->assertText("core.entity_view_display.node.{$node_type->id()}.default");
+    $this->assertText("core.entity_form_display.node.{$node_type->id()}.default");
 
     // Attempt to import configuration and verify that an error message appears
     // and the node type, body field and entity displays are still scheduled for
@@ -435,22 +435,22 @@ public function testEntityBundleDelete() {
     $this->drupalPostForm(NULL, array(), t('Import all'));
     $validation_message = t('Entities exist of type %entity_type and %bundle_label %bundle. These entities need to be deleted before importing.', array('%entity_type' => $node->getEntityType()->getLabel(), '%bundle_label' => $node->getEntityType()->getBundleLabel(), '%bundle' => $node_type->label()));
     $this->assertRaw($validation_message);
-    $this->assertText(format_string('node.type.@type', array('@type' => $node_type->id())));
-    $this->assertText(format_string('field.field.node.@type.body', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_view_display.node.@type.teaser', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_view_display.node.@type.default', array('@type' => $node_type->id())));
-    $this->assertText(format_string('core.entity_form_display.node.@type.default', array('@type' => $node_type->id())));
+    $this->assertText("node.type.{$node_type->id()}");
+    $this->assertText("field.field.node.{$node_type->id()}.body");
+    $this->assertText("core.entity_view_display.node.{$node_type->id()}.teaser");
+    $this->assertText("core.entity_view_display.node.{$node_type->id()}.default");
+    $this->assertText("core.entity_form_display.node.{$node_type->id()}.default");
 
     // Delete the node and try to import again.
     $node->delete();
     $this->drupalPostForm(NULL, array(), t('Import all'));
     $this->assertNoRaw($validation_message);
     $this->assertText(t('There are no configuration changes to import.'));
-    $this->assertNoText(format_string('node.type.@type', array('@type' => $node_type->id())));
-    $this->assertNoText(format_string('field.field.node.@type.body', array('@type' => $node_type->id())));
-    $this->assertNoText(format_string('core.entity_view_display.node.@type.teaser', array('@type' => $node_type->id())));
-    $this->assertNoText(format_string('core.entity_view_display.node.@type.default', array('@type' => $node_type->id())));
-    $this->assertNoText(format_string('core.entity_form_display.node.@type.default', array('@type' => $node_type->id())));
+    $this->assertNoText("node.type.{$node_type->id()}");
+    $this->assertNoText("field.field.node.{$node_type->id()}.body");
+    $this->assertNoText("core.entity_view_display.node.{$node_type->id()}.teaser");
+    $this->assertNoText("core.entity_view_display.node.{$node_type->id()}.default");
+    $this->assertNoText("core.entity_form_display.node.{$node_type->id()}.default");
   }
 
   /**
diff --git a/core/modules/image/src/Tests/ImageAdminStylesTest.php b/core/modules/image/src/Tests/ImageAdminStylesTest.php
index 194c016..2998eba 100644
--- a/core/modules/image/src/Tests/ImageAdminStylesTest.php
+++ b/core/modules/image/src/Tests/ImageAdminStylesTest.php
@@ -58,7 +58,7 @@ function testNumericStyleName() {
     $this->drupalPostForm('admin/config/media/image-styles/add', $edit, t('Create new style'));
     $this->assertRaw(t('Style %name was created.', array('%name' => $style_label)));
     $options = image_style_options();
-    $this->assertTrue(array_key_exists($style_name, $options), format_string('Array key %key exists.', array('%key' => $style_name)));
+    $this->assertTrue(array_key_exists($style_name, $options), "Array key $style_name exists.");
   }
 
   /**
@@ -150,18 +150,13 @@ function testStyle() {
       $uuids[$effect->getPluginId()] = $uuid;
       $effect_configuration = $effect->getConfiguration();
       foreach ($effect_edits[$effect->getPluginId()] as $field => $value) {
-        $this->assertEqual($value, $effect_configuration['data'][$field], SafeMarkup::format('The %field field in the %effect effect has the correct value of %value.', array('%field' => $field, '%effect' => $effect->getPluginId(), '%value' => $value)));
+        $this->assertEqual($value, $effect_configuration['data'][$field], "The $field field in the {$effect->getPluginId()} effect has the correct value of $value.");
       }
     }
 
     // Assert that every effect was saved.
     foreach (array_keys($effect_edits) as $effect_name) {
-      $this->assertTrue(isset($uuids[$effect_name]), format_string(
-        'A %effect_name effect was saved with ID %uuid',
-        array(
-          '%effect_name' => $effect_name,
-          '%uuid' => $uuids[$effect_name],
-        )));
+      $this->assertTrue(isset($uuids[$effect_name]), "A $effect_name effect was saved with ID $uuids[$effect_name]");
     }
 
     // Image style overview form (ordering and renaming).
@@ -195,7 +190,7 @@ function testStyle() {
 
     // Create an image to make sure it gets flushed after saving.
     $image_path = $this->createSampleImage($style);
-    $this->assertEqual($this->getImageCount($style), 1, format_string('Image style %style image %file successfully generated.', array('%style' => $style->label(), '%file' => $image_path)));
+    $this->assertEqual($this->getImageCount($style), 1, "Image style {$style->label()} image {$image_path} successfully generated.");
 
     $this->drupalPostForm($style_path, $edit, t('Update style'));
 
@@ -205,12 +200,12 @@ function testStyle() {
     // Check that the URL was updated.
     $this->drupalGet($style_path);
     $this->assertTitle(t('Edit style @name | Drupal', array('@name' => $style_label)));
-    $this->assertResponse(200, format_string('Image style %original renamed to %new', array('%original' => $style->id(), '%new' => $style_name)));
+    $this->assertResponse(200, "Image style {$style->id()} renamed to $style_name");
 
     // Check that the image was flushed after updating the style.
     // This is especially important when renaming the style. Make sure that
     // the old image directory has been deleted.
-    $this->assertEqual($this->getImageCount($style), 0, format_string('Image style %style was flushed after renaming the style and updating the order of effects.', array('%style' => $style->label())));
+    $this->assertEqual($this->getImageCount($style), 0, "Image style {$style->label()} was flushed after renaming the style and updating the order of effects.");
 
     // Load the style by the new name with the new weights.
     $style = ImageStyle::load($style_name);
@@ -231,7 +226,7 @@ function testStyle() {
 
     // Create an image to make sure it gets flushed after deleting an effect.
     $image_path = $this->createSampleImage($style);
-    $this->assertEqual($this->getImageCount($style), 1, format_string('Image style %style image %file successfully generated.', array('%style' => $style->label(), '%file' => $image_path)));
+    $this->assertEqual($this->getImageCount($style), 1, "Image style {$style->label()} image $image_path successfully generated.");
 
     // Delete the 'image_crop' effect from the style.
     $this->drupalPostForm($style_path . '/effects/' . $uuids['image_crop'] . '/delete', array(), t('Delete'));
@@ -244,12 +239,7 @@ function testStyle() {
     // Refresh the image style information and verify that the effect was
     // actually deleted.
     $style = entity_load_unchanged('image_style', $style->id());
-    $this->assertFalse($style->getEffects()->has($uuids['image_crop']), format_string(
-      'Effect with ID %uuid no longer found on image style %style',
-      array(
-        '%uuid' => $uuids['image_crop'],
-        '%style' => $style->label(),
-      )));
+    $this->assertFalse($style->getEffects()->has($uuids['image_crop']), "Effect with ID {$uuids['image_crop']} no longer found on image style {$style->label()}");
 
     // Additional test on Rotate effect, for transparent background.
     $edit = array(
@@ -269,9 +259,8 @@ function testStyle() {
 
     // Confirm the style directory has been removed.
     $directory = file_default_scheme() . '://styles/' . $style_name;
-    $this->assertFalse(is_dir($directory), format_string('Image style %style directory removed on style deletion.', array('%style' => $style->label())));
-
-    $this->assertFalse(ImageStyle::load($style_name), format_string('Image style %style successfully deleted.', array('%style' => $style->label())));
+    $this->assertFalse(is_dir($directory), "Image style{$style->label()} directory removed on {$style->label()} deletion.");
+    $this->assertFalse(ImageStyle::load($style_name), "Image style {$style->label()} successfully deleted.");
 
   }
 
@@ -307,7 +296,7 @@ function testStyleReplacement() {
 
     // Test that image is displayed using newly created style.
     $this->drupalGet('node/' . $nid);
-    $this->assertRaw($style->buildUrl($original_uri), format_string('Image displayed using style @style.', array('@style' => $style_name)));
+    $this->assertRaw($style->buildUrl($original_uri), "Image displayed using style $style_name.");
 
     // Rename the style and make sure the image field is updated.
     $new_style_name = strtolower($this->randomMachineName(10));
@@ -317,7 +306,7 @@ function testStyleReplacement() {
       'label' => $new_style_label,
     );
     $this->drupalPostForm($style_path . $style_name, $edit, t('Update style'));
-    $this->assertText(t('Changes to the style have been saved.'), format_string('Style %name was renamed to %new_name.', array('%name' => $style_name, '%new_name' => $new_style_name)));
+    $this->assertText(t('Changes to the style have been saved.'), "Style $style_name was renamed to $new_style_name.");
     $this->drupalGet('node/' . $nid);
 
     // Reload the image style using the new name.
@@ -441,7 +430,7 @@ function testConfigImport() {
 
     // Test that image is displayed using newly created style.
     $this->drupalGet('node/' . $nid);
-    $this->assertRaw($style->buildUrl($original_uri), format_string('Image displayed using style @style.', array('@style' => $style_name)));
+    $this->assertRaw($style->buildUrl($original_uri), "Image displayed using style $style_name.");
 
     // Copy config to staging, and delete the image style.
     $staging = $this->container->get('config.storage.staging');
diff --git a/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php b/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
index e541c27..68fefee 100644
--- a/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
+++ b/core/modules/image/src/Tests/ImageFieldDefaultImagesTest.php
@@ -112,20 +112,14 @@ public function testDefaultImages() {
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field']->id(),
-      format_string(
-        'Article image field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field']->id())
-      )
+      "Article image field default equals expected file ID of {$default_images['field']->id()}."
     );
     // Confirm the defaults are present on the article field edit form.
     $this->drupalGet("admin/structure/types/manage/article/fields/$field_id");
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field']->id(),
-      format_string(
-        'Article image field field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field']->id())
-      )
+      "Article image field field default equals expected file ID of {$default_images['field']->id()}."
     );
 
     // Confirm the defaults are present on the page field settings form.
@@ -133,10 +127,7 @@ public function testDefaultImages() {
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field']->id(),
-      format_string(
-        'Page image field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field']->id())
-      )
+      "Page image field default equals expected file ID of {$default_images['field']->id()}."
     );
     // Confirm the defaults are present on the page field edit form.
     $field2_id = $field2->id();
@@ -144,10 +135,7 @@ public function testDefaultImages() {
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field2']->id(),
-      format_string(
-        'Page image field field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field2']->id())
-      )
+      "Page image field field default equals expected file ID of {$default_images['field2']->id()}."
     );
 
     // Confirm that the image default is shown for a new article node.
@@ -156,10 +144,7 @@ public function testDefaultImages() {
     $this->assertEqual(
       $article_built[$field_name][0]['#item']->target_id,
       $default_images['field']->id(),
-      format_string(
-        'A new article node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field']->id())
-      )
+      "A new article node without an image has the expected default image file ID of {$default_images['field']->id()}."
     );
 
     // Confirm that the image default is shown for a new page node.
@@ -168,10 +153,7 @@ public function testDefaultImages() {
     $this->assertEqual(
       $page_built[$field_name][0]['#item']->target_id,
       $default_images['field2']->id(),
-      format_string(
-        'A new page node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field2']->id())
-      )
+      "A new page node without an image has the expected default image file ID of {$default_images['field2']->id()}."
     );
 
     // Upload a new default for the field storage.
@@ -185,10 +167,7 @@ public function testDefaultImages() {
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field_new']->id(),
-      format_string(
-        'Updated image field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field_new']->id())
-      )
+      "Updated image field default equals expected file ID of {$default_images['field_new']->id()}."
     );
 
     // Reload the nodes and confirm the field field defaults are used.
@@ -198,18 +177,12 @@ public function testDefaultImages() {
     $this->assertEqual(
       $article_built[$field_name][0]['#item']->target_id,
       $default_images['field']->id(),
-      format_string(
-        'An existing article node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field']->id())
-      )
+      "An existing article node without an image has the expected default image file ID of {$default_images['field']->id()}."
     );
     $this->assertEqual(
       $page_built[$field_name][0]['#item']->target_id,
       $default_images['field2']->id(),
-      format_string(
-        'An existing page node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field2']->id())
-      )
+      "An existing page node without an image has the expected default image file ID of {$default_images['field2']->id()}."
     );
 
     // Upload a new default for the article's field field.
@@ -224,10 +197,7 @@ public function testDefaultImages() {
     $this->assertFieldByXpath(
       '//input[@name="settings[default_image][uuid][fids]"]',
       $default_images['field_new']->id(),
-      format_string(
-        'Updated article image field field default equals expected file ID of @fid.',
-        array('@fid' => $default_images['field_new']->id())
-      )
+      "Updated article image field field default equals expected file ID of {$default_images['field_new']->id()}."
     );
 
     // Reload the nodes.
@@ -239,19 +209,13 @@ public function testDefaultImages() {
     $this->assertEqual(
       $article_built[$field_name][0]['#item']->target_id,
       $default_images['field_new']->id(),
-      format_string(
-        'An existing article node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field_new']->id())
-      )
+      "An existing article node without an image has the expected default image file ID of {$default_images['field_new']->id()}."
     );
     // Confirm the page remains unchanged.
     $this->assertEqual(
       $page_built[$field_name][0]['#item']->target_id,
       $default_images['field2']->id(),
-      format_string(
-        'An existing page node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field2']->id())
-      )
+      "An existing page node without an image has the expected default image file ID of {$default_images['field2']->id()}."
     );
 
     // Confirm the default image is shown on the node form.
@@ -281,19 +245,13 @@ public function testDefaultImages() {
     $this->assertEqual(
       $article_built[$field_name][0]['#item']->target_id,
       $default_images['field_new']->id(),
-      format_string(
-        'An existing article node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field_new']->id())
-      )
+      "An existing article node without an image has the expected default image file ID of {$default_images['field_new']->id()}."
     );
     // Confirm the page remains unchanged.
     $this->assertEqual(
       $page_built[$field_name][0]['#item']->target_id,
       $default_images['field2']->id(),
-      format_string(
-        'An existing page node without an image has the expected default image file ID of @fid.',
-        array('@fid' => $default_images['field2']->id())
-      )
+      "An existing page node without an image has the expected default image file ID of {$default_images['field2']->id()}."
     );
 
     $non_image = $this->drupalGetTestFiles('text');
diff --git a/core/modules/image/src/Tests/ImageFieldDisplayTest.php b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
index 1e1d798..645da4b 100644
--- a/core/modules/image/src/Tests/ImageFieldDisplayTest.php
+++ b/core/modules/image/src/Tests/ImageFieldDisplayTest.php
@@ -307,7 +307,7 @@ function testImageFieldSettings() {
     $this->drupalPostForm('node/' . $node->id() . '/edit', $edit, t('Save and keep published'));
     // Add the required alt text.
     $this->drupalPostForm(NULL, [$field_name . '[1][alt]' => $alt], t('Save and keep published'));
-    $this->assertText(format_string('Article @title has been updated.', array('@title' => $node->getTitle())));
+    $this->assertText("Article {$node->getTitle()} has been updated.");
 
     // Assert ImageWidget::process() calls FieldWidget::process().
     $this->drupalGet('node/' . $node->id() . '/edit');
diff --git a/core/modules/image/src/Tests/ImageStyleFlushTest.php b/core/modules/image/src/Tests/ImageStyleFlushTest.php
index 0a6a5fa..4cc3ce2 100644
--- a/core/modules/image/src/Tests/ImageStyleFlushTest.php
+++ b/core/modules/image/src/Tests/ImageStyleFlushTest.php
@@ -87,11 +87,11 @@ function testFlush() {
     $image_path = $this->createSampleImage($style, 'public');
     // Expecting to find 2 images, one is the sample.png image shown in
     // image style preview.
-    $this->assertEqual($this->getImageCount($style, 'public'), 2, format_string('Image style %style image %file successfully generated.', array('%style' => $style->label(), '%file' => $image_path)));
+    $this->assertEqual($this->getImageCount($style, 'public'), 2, "Image style {$style->label()} image $image_path successfully generated.");
 
     // Create an image for the 'private' wrapper.
     $image_path = $this->createSampleImage($style, 'private');
-    $this->assertEqual($this->getImageCount($style, 'private'), 1, format_string('Image style %style image %file successfully generated.', array('%style' => $style->label(), '%file' => $image_path)));
+    $this->assertEqual($this->getImageCount($style, 'private'), 1, "Image style {$style->label()} image $image_path successfully generated.");
 
     // Remove the 'image_scale' effect and updates the style, which in turn
     // forces an image style flush.
@@ -106,9 +106,9 @@ function testFlush() {
     $this->assertResponse(200);
 
     // Post flush, expected 1 image in the 'public' wrapper (sample.png).
-    $this->assertEqual($this->getImageCount($style, 'public'), 1, format_string('Image style %style flushed correctly for %wrapper wrapper.', array('%style' => $style->label(), '%wrapper' => 'public')));
+    $this->assertEqual($this->getImageCount($style, 'public'), 1, "Image style {$style->label()} flushed correctly for public wrapper.");
 
     // Post flush, expected no image in the 'private' wrapper.
-    $this->assertEqual($this->getImageCount($style, 'private'), 0, format_string('Image style %style flushed correctly for %wrapper wrapper.', array('%style' => $style->label(), '%wrapper' => 'private')));
+    $this->assertEqual($this->getImageCount($style, 'private'), 0, "Image style {$style->label()} flushed correctly for private wrapper.");
   }
 }
diff --git a/core/modules/system/src/Tests/Entity/EntityFieldTest.php b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
index 5414730..634fb1e 100644
--- a/core/modules/system/src/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
@@ -109,66 +109,66 @@ protected function doTestReadWrite($entity_type) {
     $langcode = 'en';
 
     // Access the name field.
-    $this->assertTrue($entity->name instanceof FieldItemListInterface, format_string('%entity_type: Field implements interface', array('%entity_type' => $entity_type)));
-    $this->assertTrue($entity->name[0] instanceof FieldItemInterface, format_string('%entity_type: Field item implements interface', array('%entity_type' => $entity_type)));
+    $this->assertTrue($entity->name instanceof FieldItemListInterface, "$entity_type: Field implements interface");
+    $this->assertTrue($entity->name[0] instanceof FieldItemInterface, "$entity_type: Field item implements interface");
 
-    $this->assertEqual($this->entityName, $entity->name->value, format_string('%entity_type: Name value can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityName, $entity->name[0]->value, format_string('%entity_type: Name value can be read through list access.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name->getValue(), array(0 => array('value' => $this->entityName)), format_string('%entity_type: Plain field value returned.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($this->entityName, $entity->name->value, "$entity_type: Name value can be read.");
+    $this->assertEqual($this->entityName, $entity->name[0]->value, "$entity_type: Name value can be read through list access.");
+    $this->assertEqual($entity->name->getValue(), array(0 => array('value' => $this->entityName)), "$entity_type: Plain field value returned.");
 
     // Change the name.
     $new_name = $this->randomMachineName();
     $entity->name->value = $new_name;
-    $this->assertEqual($new_name, $entity->name->value, format_string('%entity_type: Name can be updated and read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name->getValue(), array(0 => array('value' => $new_name)), format_string('%entity_type: Plain field value reflects the update.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_name, $entity->name->value, "$entity_type: Name can be updated and read.");
+    $this->assertEqual($entity->name->getValue(), array(0 => array('value' => $new_name)), "$entity_type: Plain field value reflects the update.");
 
     $new_name = $this->randomMachineName();
     $entity->name[0]->value = $new_name;
-    $this->assertEqual($new_name, $entity->name->value, format_string('%entity_type: Name can be updated and read through list access.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_name, $entity->name->value, "$entity_type: Name can be updated and read through list access.");
 
     // Access the user field.
-    $this->assertTrue($entity->user_id instanceof FieldItemListInterface, format_string('%entity_type: Field implements interface', array('%entity_type' => $entity_type)));
-    $this->assertTrue($entity->user_id[0] instanceof FieldItemInterface, format_string('%entity_type: Field item implements interface', array('%entity_type' => $entity_type)));
+    $this->assertTrue($entity->user_id instanceof FieldItemListInterface, "$entity_type: Field implements interface");
+    $this->assertTrue($entity->user_id[0] instanceof FieldItemInterface, "$entity_type: Field item implements interface");
 
-    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, format_string('%entity_type: User id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: User name can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, "$entity_type: User id can be read.");
+    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, "$entity_type: User name can be read.");
 
     // Change the assigned user by entity.
     $new_user1 = $this->createUser();
     $entity->user_id->entity = $new_user1;
-    $this->assertEqual($new_user1->id(), $entity->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user1->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: Updated username value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user1->id(), $entity->user_id->target_id, "$entity_type: Updated user id can be read.");
+    $this->assertEqual($new_user1->getUsername(), $entity->user_id->entity->name->value, "$entity_type: Updated username value can be read.");
 
     // Change the assigned user by id.
     $new_user2 = $this->createUser();
     $entity->user_id->target_id = $new_user2->id();
-    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: Updated username value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, "$entity_type: Updated user id can be read.");
+    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, "$entity_type: Updated username value can be read.");
 
     // Try unsetting a field property.
     $entity->name->value = NULL;
     $entity->user_id->target_id = NULL;
-    $this->assertNull($entity->name->value, format_string('%entity_type: Name field is not set.', array('%entity_type' => $entity_type)));
-    $this->assertNull($entity->user_id->target_id, format_string('%entity_type: User ID field is not set.', array('%entity_type' => $entity_type)));
-    $this->assertNull($entity->user_id->entity, format_string('%entity_type: User entity field is not set.', array('%entity_type' => $entity_type)));
+    $this->assertNull($entity->name->value, "$entity_type: Name field is not set.");
+    $this->assertNull($entity->user_id->target_id, "$entity_type: User ID field is not set.");
+    $this->assertNull($entity->user_id->entity, "$entity_type: User entity field is not set.");
 
     // Test setting the values via the typed data API works as well.
     // Change the assigned user by entity.
     $entity->user_id->first()->get('entity')->setValue($new_user2);
-    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: Updated user name value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, "$entity_type: Updated user id can be read.");
+    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, "$entity_type: Updated user name value can be read.");
 
     // Change the assigned user by id.
     $entity->user_id->first()->get('target_id')->setValue($new_user2->id());
-    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: Updated user name value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user2->id(), $entity->user_id->target_id, "$entity_type: Updated user id can be read.");
+    $this->assertEqual($new_user2->getUsername(), $entity->user_id->entity->name->value, "$entity_type: Updated user name value can be read.");
 
     // Try unsetting a field.
     $entity->name->first()->get('value')->setValue(NULL);
     $entity->user_id->first()->get('target_id')->setValue(NULL);
-    $this->assertNull($entity->name->value, format_string('%entity_type: Name field is not set.', array('%entity_type' => $entity_type)));
-    $this->assertNull($entity->user_id->target_id, format_string('%entity_type: User ID field is not set.', array('%entity_type' => $entity_type)));
-    $this->assertNull($entity->user_id->entity, format_string('%entity_type: User entity field is not set.', array('%entity_type' => $entity_type)));
+    $this->assertNull($entity->name->value, "$entity_type: Name field is not set.");
+    $this->assertNull($entity->user_id->target_id, "$entity_type: User ID field is not set.");
+    $this->assertNull($entity->user_id->entity, "$entity_type: User entity field is not set.");
 
     // Create a fresh entity so target_id does not get its property object
     // instantiated, then verify setting a new value via typed data API works.
@@ -177,38 +177,38 @@ protected function doTestReadWrite($entity_type) {
     ));
     // Access the property object, and set a value.
     $entity2->user_id->first()->get('target_id')->setValue($new_user2->id());
-    $this->assertEqual($new_user2->id(), $entity2->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user2->name->value, $entity2->user_id->entity->name->value, format_string('%entity_type: Updated user name value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user2->id(), $entity2->user_id->target_id, "$entity_type: Updated user id can be read.");
+    $this->assertEqual($new_user2->name->value, $entity2->user_id->entity->name->value, "$entity_type: Updated user name value can be read.");
 
     // Test using isset(), empty() and unset().
     $entity->name->value = 'test unset';
     unset($entity->name->value);
-    $this->assertFalse(isset($entity->name->value), format_string('%entity_type: Name is not set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(isset($entity->name[0]->value), format_string('%entity_type: Name is not set.', array('%entity_type' => $entity_type)));
-    $this->assertTrue(empty($entity->name->value), format_string('%entity_type: Name is empty.', array('%entity_type' => $entity_type)));
-    $this->assertTrue(empty($entity->name[0]->value), format_string('%entity_type: Name is empty.', array('%entity_type' => $entity_type)));
+    $this->assertFalse(isset($entity->name->value), "$entity_type: Name is not set");
+    $this->assertFalse(isset($entity->name[0]->value), "$entity_type: Name is not set");
+    $this->assertTrue(empty($entity->name->value), "$entity_type: Name is empty");
+    $this->assertTrue(empty($entity->name[0]->value), "$entity_type: Name is empty");
 
     $entity->name->value = 'a value';
-    $this->assertTrue(isset($entity->name->value), format_string('%entity_type: Name is set.', array('%entity_type' => $entity_type)));
-    $this->assertTrue(isset($entity->name[0]->value), format_string('%entity_type: Name is set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(empty($entity->name->value), format_string('%entity_type: Name is not empty.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(empty($entity->name[0]->value), format_string('%entity_type: Name is not empty.', array('%entity_type' => $entity_type)));
-    $this->assertTrue(isset($entity->name[0]), format_string('%entity_type: Name string item is set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(isset($entity->name[1]), format_string('%entity_type: Second name string item is not set as it does not exist', array('%entity_type' => $entity_type)));
-    $this->assertTrue(isset($entity->name), format_string('%entity_type: Name field is set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(isset($entity->nameInvalid), format_string('%entity_type: Not existing field is not set.', array('%entity_type' => $entity_type)));
+    $this->assertTrue(isset($entity->name->value), "$entity_type: Name is set");
+    $this->assertTrue(isset($entity->name[0]->value), "$entity_type: Name is set.");
+    $this->assertFalse(empty($entity->name->value), "$entity_type: Name is not empty");
+    $this->assertFalse(empty($entity->name[0]->value), "$entity_type: Name is not empty");
+    $this->assertTrue(isset($entity->name[0]), "$entity_type: Name string item is set.");
+    $this->assertFalse(isset($entity->name[1]), "$entity_type: Second name string item is not set as it does not exist");
+    $this->assertTrue(isset($entity->name), "$entity_type: Name field is set");
+    $this->assertFalse(isset($entity->nameInvalid), "$entity_type: Not existing field is not set.");
 
     unset($entity->name[0]);
-    $this->assertFalse(isset($entity->name[0]), format_string('%entity_type: Name field item is not set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(isset($entity->name[0]->value), format_string('%entity_type: Name is not set.', array('%entity_type' => $entity_type)));
-    $this->assertFalse(isset($entity->name->value), format_string('%entity_type: Name is not set.', array('%entity_type' => $entity_type)));
+    $this->assertFalse(isset($entity->name[0]), "$entity_type: Name field item is not set.");
+    $this->assertFalse(isset($entity->name[0]->value), "$entity_type: Name is not set");
+    $this->assertFalse(isset($entity->name->value), "$entity_type: Name is not set");
 
     // Test emptying a field by assigning an empty value. NULL and array()
     // behave the same.
     foreach ([NULL, array(), 'unset'] as $empty) {
       // Make sure a value is present
       $entity->name->value = 'a value';
-      $this->assertTrue(isset($entity->name->value), format_string('%entity_type: Name is set.', array('%entity_type' => $entity_type)));
+      $this->assertTrue(isset($entity->name->value), "$entity_type: Name is set");
       // Now, empty the field.
       if ($empty === 'unset') {
         unset($entity->name);
@@ -216,36 +216,36 @@ protected function doTestReadWrite($entity_type) {
       else {
         $entity->name = $empty;
       }
-      $this->assertTrue(isset($entity->name), format_string('%entity_type: Name field is set.', array('%entity_type' => $entity_type)));
-      $this->assertTrue($entity->name->isEmpty(), format_string('%entity_type: Name field is set.', array('%entity_type' => $entity_type)));
-      $this->assertIdentical(count($entity->name), 0, format_string('%entity_type: Name field contains no items.', array('%entity_type' => $entity_type)));
-      $this->assertIdentical($entity->name->getValue(), array(), format_string('%entity_type: Name field value is an empty array.', array('%entity_type' => $entity_type)));
-      $this->assertFalse(isset($entity->name[0]), format_string('%entity_type: Name field item is not set.', array('%entity_type' => $entity_type)));
-      $this->assertFalse(isset($entity->name[0]->value), format_string('%entity_type: First name item value is not set.', array('%entity_type' => $entity_type)));
-      $this->assertFalse(isset($entity->name->value), format_string('%entity_type: Name value is not set.', array('%entity_type' => $entity_type)));
+      $this->assertTrue(isset($entity->name), "$entity_type: Name field is set");
+      $this->assertTrue($entity->name->isEmpty(), "$entity_type: Name field is set");
+      $this->assertIdentical(count($entity->name), 0, "$entity_type: Name field contains no items.");
+      $this->assertIdentical($entity->name->getValue(), array(), "$entity_type: Name field value is an empty array.");
+      $this->assertFalse(isset($entity->name[0]), "$entity_type: Name field item is not set.");
+      $this->assertFalse(isset($entity->name[0]->value), "$entity_type: First name item value is not set.");
+      $this->assertFalse(isset($entity->name->value), "$entity_type: Name value is not set.");
     }
 
     // Access the language field.
     $langcode_key = $this->entityManager->getDefinition($entity_type)->getKey('langcode');
-    $this->assertEqual($langcode, $entity->{$langcode_key}->value, format_string('%entity_type: Language code can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(\Drupal::languageManager()->getLanguage($langcode), $entity->{$langcode_key}->language, format_string('%entity_type: Language object can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($langcode, $entity->{$langcode_key}->value, "$entity_type: Language object can be read.");
+    $this->assertEqual(\Drupal::languageManager()->getLanguage($langcode), $entity->{$langcode_key}->language, "$entity_type: Language object can be read.");
 
     // Change the language by code.
     $entity->{$langcode_key}->value = \Drupal::languageManager()->getDefaultLanguage()->getId();
-    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage()->getId(), $entity->{$langcode_key}->value, format_string('%entity_type: Language code can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage(), $entity->{$langcode_key}->language, format_string('%entity_type: Language object can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage()->getId(), $entity->{$langcode_key}->value, "$entity_type: Language object can be read.");
+    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage(), $entity->{$langcode_key}->language, "$entity_type: Language object can be read.");
 
     // Revert language by code then try setting it by language object.
     $entity->{$langcode_key}->value = $langcode;
     $entity->{$langcode_key}->language = \Drupal::languageManager()->getDefaultLanguage();
-    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage()->getId(), $entity->{$langcode_key}->value, format_string('%entity_type: Language code can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage(), $entity->{$langcode_key}->language, format_string('%entity_type: Language object can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage()->getId(), $entity->{$langcode_key}->value, "$entity_type: Language object can be read.");
+    $this->assertEqual(\Drupal::languageManager()->getDefaultLanguage(), $entity->{$langcode_key}->language, "$entity_type: Language object can be read.");
 
     // Access the text field and test updating.
-    $this->assertEqual($entity->field_test_text->value, $this->entityFieldText, format_string('%entity_type: Text field can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->field_test_text->value, $this->entityFieldText, "$entity_type: Text field can be read.");
     $new_text = $this->randomMachineName();
     $entity->field_test_text->value = $new_text;
-    $this->assertEqual($entity->field_test_text->value, $new_text, format_string('%entity_type: Updated text field can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->field_test_text->value, $new_text, "$entity_type: Updated text field can be read.");
 
     // Test creating the entity by passing in plain values.
     $this->entityName = $this->randomMachineName();
@@ -260,70 +260,70 @@ protected function doTestReadWrite($entity_type) {
       'user_id' => $user_item,
       'field_test_text' => $text_item,
     ));
-    $this->assertEqual($this->entityName, $entity->name->value, format_string('%entity_type: Name value can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, format_string('%entity_type: User id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: User name can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityFieldText, $entity->field_test_text->value, format_string('%entity_type: Text field can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($this->entityName, $entity->name->value, "$entity_type: Name value can be read.");
+    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, "$entity_type: User id can be read.");
+    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, "$entity_type: User name can be read.");
+    $this->assertEqual($this->entityFieldText, $entity->field_test_text->value, "$entity_type: Text field can be read.");
 
     // Tests copying field values by assigning the TypedData objects.
     $entity2 = $this->createTestEntity($entity_type);
     $entity2->name = $entity->name;
     $entity2->user_id = $entity->user_id;
     $entity2->field_test_text = $entity->field_test_text;
-    $this->assertFalse($entity->name === $entity2->name, format_string('%entity_type: Copying properties results in a different field object.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name->value, $entity2->name->value, format_string('%entity_type: Name field copied.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->user_id->target_id, $entity2->user_id->target_id, format_string('%entity_type: User id field copied.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->field_test_text->value, $entity2->field_test_text->value, format_string('%entity_type: Text field copied.', array('%entity_type' => $entity_type)));
+    $this->assertFalse($entity->name === $entity2->name, "$entity_type: Copying properties results in a different field object.");
+    $this->assertEqual($entity->name->value, $entity2->name->value, "$entity_type: Name field copied.");
+    $this->assertEqual($entity->user_id->target_id, $entity2->user_id->target_id, "$entity_type: User id field copied.");
+    $this->assertEqual($entity->field_test_text->value, $entity2->field_test_text->value, "$entity_type: Text field copied.");
 
     // Tests that assigning TypedData objects to non-field properties keeps the
     // assigned value as is.
     $entity2 = $this->createTestEntity($entity_type);
     $entity2->_not_a_field = $entity->name;
-    $this->assertTrue($entity2->_not_a_field === $entity->name, format_string('%entity_type: Typed data objects can be copied to non-field properties as is.', array('%entity_type' => $entity_type)));
+    $this->assertTrue($entity2->_not_a_field === $entity->name, "$entity_type: Typed data objects can be copied to non-field properties as is.");
 
     // Tests adding a value to a field item list.
     $entity->name[] = 'Another name';
-    $this->assertEqual($entity->name[1]->value, 'Another name', format_string('%entity_type: List item added via [] and the first property.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->name[1]->value, 'Another name', "$entity_type: List item added via [] and the first property.");
     $entity->name[] = array('value' => 'Third name');
-    $this->assertEqual($entity->name[2]->value, 'Third name', format_string('%entity_type: List item added via [] and an array of properties.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->name[2]->value, 'Third name', "$entity_type: List item added via [] and an array of properties.");
     $entity->name[3] = array('value' => 'Fourth name');
-    $this->assertEqual($entity->name[3]->value, 'Fourth name', format_string('%entity_type: List item added via offset and an array of properties.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->name[3]->value, 'Fourth name', "$entity_type: List item added via offset and an array of properties.");
     unset($entity->name[3]);
 
     // Test removing and empty-ing list items.
-    $this->assertEqual(count($entity->name), 3, format_string('%entity_type: List has 3 items.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entity->name), 3, "$entity_type: List has 3 items.");
     unset($entity->name[1]);
-    $this->assertEqual(count($entity->name), 2, format_string('%entity_type: Second list item has been removed.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name[1]->value, 'Third name', format_string('%entity_type: The subsequent items have been shifted up.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name[1]->getName(), 1, format_string('%entity_type: The items names have been updated to their new delta.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entity->name), 2, "$entity_type: Second list item has been removed.");
+    $this->assertEqual($entity->name[1]->value, 'Third name', "$entity_type: The subsequent items have been shifted up.");
+    $this->assertEqual($entity->name[1]->getName(), 1, "$entity_type: The items names have been updated to their new delta.");
     $entity->name[1] = NULL;
-    $this->assertEqual(count($entity->name), 2, format_string('%entity_type: Assigning NULL does not reduce array count.', array('%entity_type' => $entity_type)));
-    $this->assertTrue($entity->name[1]->isEmpty(), format_string('%entity_type: Assigning NULL empties the item.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entity->name), 2, "$entity_type: Assigning NULL does not reduce array count.");
+    $this->assertTrue($entity->name[1]->isEmpty(), "$entity_type: Assigning NULL empties the item.");
 
     // Test using isEmpty().
     unset($entity->name[1]);
-    $this->assertFalse($entity->name[0]->isEmpty(), format_string('%entity_type: Name item is not empty.', array('%entity_type' => $entity_type)));
+    $this->assertFalse($entity->name[0]->isEmpty(), "$entity_type: Name item is not empty.");
     $entity->name->value = NULL;
-    $this->assertTrue($entity->name[0]->isEmpty(), format_string('%entity_type: Name item is empty.', array('%entity_type' => $entity_type)));
-    $this->assertTrue($entity->name->isEmpty(), format_string('%entity_type: Name field is empty.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(count($entity->name), 1, format_string('%entity_type: Empty item is considered when counting.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(count(iterator_to_array($entity->name->getIterator())), count($entity->name), format_string('%entity_type: Count matches iterator count.', array('%entity_type' => $entity_type)));
-    $this->assertTrue($entity->name->getValue() === array(0 => array('value' => NULL)), format_string('%entity_type: Name field value contains a NULL value.', array('%entity_type' => $entity_type)));
+    $this->assertTrue($entity->name[0]->isEmpty(), "$entity_type: Name item is empty.");
+    $this->assertTrue($entity->name->isEmpty(), "$entity_type: Name field is empty.");
+    $this->assertEqual(count($entity->name), 1, "$entity_type: Empty item is considered when counting.");
+    $this->assertEqual(count(iterator_to_array($entity->name->getIterator())), count($entity->name), "$entity_type: Count matches iterator count.");
+    $this->assertTrue($entity->name->getValue() === array(0 => array('value' => NULL)), "$entity_type: Name field value contains a NULL value.");
 
     // Test using filterEmptyItems().
     $entity->name = array(NULL, 'foo');
-    $this->assertEqual(count($entity->name), 2, format_string('%entity_type: List has 2 items.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entity->name), 2, "$entity_type: List has 2 items.");
     $entity->name->filterEmptyItems();
-    $this->assertEqual(count($entity->name), 1, format_string('%entity_type: The empty item was removed.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name[0]->value, 'foo', format_string('%entity_type: The items were renumbered.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($entity->name[0]->getName(), 0, format_string('%entity_type: The deltas were updated in the items.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entity->name), 1, "$entity_type: The empty item was removed.");
+    $this->assertEqual($entity->name[0]->value, 'foo', "$entity_type: The items were renumbered.");
+    $this->assertEqual($entity->name[0]->getName(), 0, "$entity_type: The deltas were updated in the items.");
 
     // Test get and set field values.
     $entity->name = 'foo';
-    $this->assertEqual($entity->name[0]->toArray(), array('value' => 'foo'), format_string('%entity_type: Field value has been retrieved via toArray()', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->name[0]->toArray(), array('value' => 'foo'), "$entity_type: Field value has been retrieved via toArray()");
 
     $values = $entity->toArray();
-    $this->assertEqual($values['name'], array(0 => array('value' => 'foo')), format_string('%entity_type: Field value has been retrieved via toArray() from an entity.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($values['name'], array(0 => array('value' => 'foo')), "$entity_type: Field value has been retrieved via toArray() from an entity.");
 
     // Make sure the user id can be set to zero.
     $user_item[0]['target_id'] = 0;
@@ -332,8 +332,8 @@ protected function doTestReadWrite($entity_type) {
       'user_id' => $user_item,
       'field_test_text' => $text_item,
     ));
-    $this->assertNotNull($entity->user_id->target_id, format_string('%entity_type: User id is not NULL', array('%entity_type' => $entity_type)));
-    $this->assertIdentical($entity->user_id->target_id, 0, format_string('%entity_type: User id has been set to 0', array('%entity_type' => $entity_type)));
+    $this->assertNotNull($entity->user_id->target_id, "$entity_type: User id is not NULL");
+    $this->assertIdentical($entity->user_id->target_id, 0, "$entity_type: User id has been set to 0");
 
     // Test setting the ID with the value only.
     $entity = entity_create($entity_type, array(
@@ -341,8 +341,8 @@ protected function doTestReadWrite($entity_type) {
       'user_id' => 0,
       'field_test_text' => $text_item,
     ));
-    $this->assertNotNull($entity->user_id->target_id, format_string('%entity_type: User id is not NULL', array('%entity_type' => $entity_type)));
-    $this->assertIdentical($entity->user_id->target_id, 0, format_string('%entity_type: User id has been set to 0', array('%entity_type' => $entity_type)));
+    $this->assertNotNull($entity->user_id->target_id, "$entity_type: User id is not NULL");
+    $this->assertIdentical($entity->user_id->target_id, 0, "$entity_type: User id has been set to 0");
   }
 
   /**
@@ -365,19 +365,19 @@ protected function doTestSave($entity_type) {
     $langcode_key = $this->entityManager->getDefinition($entity_type)->getKey('langcode');
     $entity = $this->createTestEntity($entity_type);
     $entity->save();
-    $this->assertTrue((bool) $entity->id(), format_string('%entity_type: Entity has received an id.', array('%entity_type' => $entity_type)));
+    $this->assertTrue((bool) $entity->id(), "$entity_type: Entity has received an id.");
 
     $entity = entity_load($entity_type, $entity->id());
-    $this->assertTrue((bool) $entity->id(), format_string('%entity_type: Entity loaded.', array('%entity_type' => $entity_type)));
+    $this->assertTrue((bool) $entity->id(), "$entity_type: Entity loaded.");
 
     // Access the name field.
-    $this->assertEqual(1, $entity->id->value, format_string('%entity_type: ID value can be read.', array('%entity_type' => $entity_type)));
-    $this->assertTrue(is_string($entity->uuid->value), format_string('%entity_type: UUID value can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual('en', $entity->{$langcode_key}->value, format_string('%entity_type: Language code can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual(\Drupal::languageManager()->getLanguage('en'), $entity->{$langcode_key}->language, format_string('%entity_type: Language object can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, format_string('%entity_type: User id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, format_string('%entity_type: User name can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($this->entityFieldText, $entity->field_test_text->value, format_string('%entity_type: Text field can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(1, $entity->id->value, "$entity_type: ID value can be read.");
+    $this->assertTrue(is_string($entity->uuid->value), "$entity_type: UUID value can be read.");
+    $this->assertEqual('en', $entity->{$langcode_key}->value, "$entity_type: Language object can be read.");
+    $this->assertEqual(\Drupal::languageManager()->getLanguage('en'), $entity->{$langcode_key}->language, "$entity_type: Language object can be read.");
+    $this->assertEqual($this->entityUser->id(), $entity->user_id->target_id, "$entity_type: User id can be read.");
+    $this->assertEqual($this->entityUser->getUsername(), $entity->user_id->entity->name->value, "$entity_type: User name can be read.");
+    $this->assertEqual($this->entityFieldText, $entity->field_test_text->value, "$entity_type: Text field can be read.");
   }
 
   /**
@@ -517,8 +517,8 @@ protected function doTestIterator($entity_type) {
     }
 
     $fields = $entity->getFields();
-    $this->assertEqual(array_keys($fields), array_keys($entity->getTypedData()->getDataDefinition()->getPropertyDefinitions()), format_string('%entity_type: All fields returned.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($fields, iterator_to_array($entity->getIterator()), format_string('%entity_type: Entity iterator iterates over all fields.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(array_keys($fields), array_keys($entity->getTypedData()->getDataDefinition()->getPropertyDefinitions()), "$entity_type: All fields returned.");
+    $this->assertEqual($fields, iterator_to_array($entity->getIterator()), "$entity_type: Entity iterator iterates over all fields.");
   }
 
   /**
@@ -560,7 +560,7 @@ protected function doTestDataStructureInterfaces($entity_type) {
     );
     asort($strings);
     asort($target_strings);
-    $this->assertEqual(array_values($strings), array_values($target_strings), format_string('%entity_type: All contained strings found.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(array_values($strings), array_values($target_strings), "$entity_type: All contained strings found.");
   }
 
   /**
@@ -730,12 +730,12 @@ protected function doTestComputedProperties($entity_type) {
     $entity->field_test_text->format = filter_default_format();
 
     $target = "<p>The &lt;strong&gt;text&lt;/strong&gt; text to filter.</p>\n";
-    $this->assertEqual($entity->field_test_text->processed, $target, format_string('%entity_type: Text is processed with the default filter.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->field_test_text->processed, $target, "$entity_type: Text is processed with the default filter.");
 
     // Save and load entity and make sure it still works.
     $entity->save();
     $entity = entity_load($entity_type, $entity->id());
-    $this->assertEqual($entity->field_test_text->processed, $target, format_string('%entity_type: Text is processed with the default filter.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->field_test_text->processed, $target, "$entity_type: Text is processed with the default filter.");
   }
 
 }
diff --git a/core/modules/system/src/Tests/Entity/EntityTranslationTest.php b/core/modules/system/src/Tests/Entity/EntityTranslationTest.php
index 21ff392..3941f25 100644
--- a/core/modules/system/src/Tests/Entity/EntityTranslationTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityTranslationTest.php
@@ -42,55 +42,55 @@ protected function doTestEntityLanguageMethods($entity_type) {
       'name' => 'test',
       'user_id' => $this->container->get('current_user')->id(),
     ));
-    $this->assertEqual($entity->language()->getId(), $this->languageManager->getDefaultLanguage()->getId(), format_string('%entity_type: Entity created with API has default language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->language()->getId(), $this->languageManager->getDefaultLanguage()->getId(), "$entity_type: Entity created with API has default language.");
     $entity = entity_create($entity_type, array(
       'name' => 'test',
       'user_id' => \Drupal::currentUser()->id(),
       $langcode_key => LanguageInterface::LANGCODE_NOT_SPECIFIED,
     ));
-    $this->assertEqual($entity->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Entity language not specified.', array('%entity_type' => $entity_type)));
-    $this->assertFalse($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED, "$entity_type: Entity language not specified.");
+    $this->assertFalse($entity->getTranslationLanguages(FALSE), "$entity_type: No translations are available");
 
     // Set the value in default language.
     $entity->set($this->fieldName, array(0 => array('value' => 'default value')));
     // Get the value.
     $field = $entity->getTranslation(LanguageInterface::LANGCODE_DEFAULT)->get($this->fieldName);
-    $this->assertEqual($field->value, 'default value', format_string('%entity_type: Untranslated value retrieved.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($field->getLangcode(), LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Field object has the expected langcode.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($field->value, 'default value', "$entity_type: Untranslated value retrieved.");
+    $this->assertEqual($field->getLangcode(), LanguageInterface::LANGCODE_NOT_SPECIFIED, "$entity_type: Field object has the expected langcode.");
 
     // Set the value in a certain language. As the entity is not
     // language-specific it should use the default language and so ignore the
     // specified language.
     $entity->getTranslation($this->langcodes[1])->set($this->fieldName, array(0 => array('value' => 'default value2')));
-    $this->assertEqual($entity->get($this->fieldName)->value, 'default value2', format_string('%entity_type: Untranslated value updated.', array('%entity_type' => $entity_type)));
-    $this->assertFalse($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->get($this->fieldName)->value, 'default value2', "$entity_type: Untranslated value updated.");
+    $this->assertFalse($entity->getTranslationLanguages(FALSE), "$entity_type: No translations are available");
 
     // Test getting a field value using a specific language for a not
     // language-specific entity.
     $field = $entity->getTranslation($this->langcodes[1])->get($this->fieldName);
-    $this->assertEqual($field->value, 'default value2', format_string('%entity_type: Untranslated value retrieved.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($field->getLangcode(), LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Field object has the expected langcode.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($field->value, 'default value2', "$entity_type: Untranslated value retrieved.");
+    $this->assertEqual($field->getLangcode(), LanguageInterface::LANGCODE_NOT_SPECIFIED, "$entity_type: Field object has the expected langcode.");
 
     // Now, make the entity language-specific by assigning a language and test
     // translating it.
     $default_langcode = $this->langcodes[0];
     $entity->{$langcode_key}->value = $default_langcode;
     $entity->{$this->fieldName} = array();
-    $this->assertEqual($entity->language(), \Drupal::languageManager()->getLanguage($this->langcodes[0]), format_string('%entity_type: Entity language retrieved.', array('%entity_type' => $entity_type)));
-    $this->assertFalse($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->language(), \Drupal::languageManager()->getLanguage($this->langcodes[0]), "$entity_type: Entity language retrieved.");
+    $this->assertFalse($entity->getTranslationLanguages(FALSE), "$entity_type: No translations are available");
 
     // Set the value in default language.
     $entity->set($this->fieldName, array(0 => array('value' => 'default value')));
     // Get the value.
     $field = $entity->get($this->fieldName);
-    $this->assertEqual($field->value, 'default value', format_string('%entity_type: Untranslated value retrieved.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($field->getLangcode(), $default_langcode, format_string('%entity_type: Field object has the expected langcode.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($field->value, 'default value', "$entity_type: Untranslated value retrieved.");
+    $this->assertEqual($field->getLangcode(), $default_langcode, "$entity_type: Field object has the expected langcode.");
 
     // Set a translation.
     $entity->getTranslation($this->langcodes[1])->set($this->fieldName, array(0 => array('value' => 'translation 1')));
     $field = $entity->getTranslation($this->langcodes[1])->{$this->fieldName};
-    $this->assertEqual($field->value, 'translation 1', format_string('%entity_type: Translated value set.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($field->getLangcode(), $this->langcodes[1], format_string('%entity_type: Field object has the expected langcode.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($field->value, 'translation 1', "$entity_type: Translated value set.");
+    $this->assertEqual($field->getLangcode(), $this->langcodes[1], "$entity_type: Field object has the expected langcode.");
 
     // Make sure the untranslated value stays.
     $field = $entity->get($this->fieldName);
@@ -101,7 +101,7 @@ protected function doTestEntityLanguageMethods($entity_type) {
     $this->assertEqual($entity->getTranslationLanguages(FALSE), $translations, 'Translations retrieved.');
 
     // Try to get a not available translation.
-    $this->assertNull($entity->getTranslation($this->langcodes[2])->get($this->fieldName)->value, format_string('%entity_type: A translation that is not available is NULL.', array('%entity_type' => $entity_type)));
+    $this->assertNull($entity->getTranslation($this->langcodes[2])->get($this->fieldName)->value, "$entity_type: A translation that is not available is NULL.");
 
     // Try to get a value using an invalid language code.
     try {
@@ -115,10 +115,10 @@ protected function doTestEntityLanguageMethods($entity_type) {
     // Try to set a value using an invalid language code.
     try {
       $entity->getTranslation('invalid')->set($this->fieldName, NULL);
-      $this->fail(format_string('%entity_type: Setting a translation for an invalid language throws an exception.', array('%entity_type' => $entity_type)));
+      $this->fail("$entity_type: Setting a translation for an invalid language throws an exception.");
     }
     catch (\InvalidArgumentException $e) {
-      $this->pass(format_string('%entity_type: Setting a translation for an invalid language throws an exception.', array('%entity_type' => $entity_type)));
+      $this->pass("$entity_type: Setting a translation for an invalid language throws an exception.");
     }
 
     // Set the value in default language.
@@ -126,8 +126,8 @@ protected function doTestEntityLanguageMethods($entity_type) {
     $entity->getTranslation($this->langcodes[1])->set($field_name, array(0 => array('value' => 'default value2')));
     // Get the value.
     $field = $entity->get($field_name);
-    $this->assertEqual($field->value, 'default value2', format_string('%entity_type: Untranslated value set into a translation in non-strict mode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($field->getLangcode(), $default_langcode, format_string('%entity_type: Field object has the expected langcode.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($field->value, 'default value2', "$entity_type: Untranslated value set into a translation in non-strict mode.");
+    $this->assertEqual($field->getLangcode(), $default_langcode, "$entity_type: Field object has the expected langcode.");
   }
 
   /**
@@ -159,19 +159,19 @@ protected function doTestMultilingualProperties($entity_type) {
     $entity->save();
     $entity = entity_load($entity_type, $entity->id());
     $default_langcode = $entity->language()->getId();
-    $this->assertEqual($default_langcode, LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Entity created as language neutral.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($default_langcode, LanguageInterface::LANGCODE_NOT_SPECIFIED, "$entity_type: Entity created as language neutral.");
     $field = $entity->getTranslation(LanguageInterface::LANGCODE_DEFAULT)->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name has been correctly stored as language neutral.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->getTranslation(LanguageInterface::LANGCODE_DEFAULT)->get('user_id')->target_id, format_string('%entity_type: The entity author has been correctly stored as language neutral.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name has been correctly stored as language neutral.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->getTranslation(LanguageInterface::LANGCODE_DEFAULT)->get('user_id')->target_id, "$entity_type: The entity author has been correctly stored as language neutral.");
     $field = $entity->getTranslation($langcode)->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name defaults to neutral language.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->getTranslation($langcode)->get('user_id')->target_id, format_string('%entity_type: The entity author defaults to neutral language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name defaults to neutral language.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->getTranslation($langcode)->get('user_id')->target_id, "$entity_type: The entity author defaults to neutral language.");
     $field = $entity->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name can be retrieved without specifying a language.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->get('user_id')->target_id, format_string('%entity_type: The entity author can be retrieved without specifying a language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name can be retrieved without specifying a language.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->get('user_id')->target_id, "$entity_type: The entity author can be retrieved without specifying a language.");
 
     // Create a language-aware entity and check that properties are stored
     // as language-aware.
@@ -179,21 +179,21 @@ protected function doTestMultilingualProperties($entity_type) {
     $entity->save();
     $entity = entity_load($entity_type, $entity->id());
     $default_langcode = $entity->language()->getId();
-    $this->assertEqual($default_langcode, $langcode, format_string('%entity_type: Entity created as language specific.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($default_langcode, $langcode, "$entity_type: Entity created as language specific.");
     $field = $entity->getTranslation($langcode)->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name has been correctly stored as a language-aware property.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->getTranslation($langcode)->get('user_id')->target_id, format_string('%entity_type: The entity author has been correctly stored as a language-aware property.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name has been correctly stored as a language-aware property.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->getTranslation($langcode)->get('user_id')->target_id, "$entity_type: The entity author has been correctly stored as a language-aware property.");
     // Translatable properties on a translatable entity should use default
     // language if LanguageInterface::LANGCODE_NOT_SPECIFIED is passed.
     $field = $entity->getTranslation(LanguageInterface::LANGCODE_NOT_SPECIFIED)->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name defaults to the default language.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->getTranslation(LanguageInterface::LANGCODE_NOT_SPECIFIED)->get('user_id')->target_id, format_string('%entity_type: The entity author defaults to the default language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name defaults to the default language.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->getTranslation(LanguageInterface::LANGCODE_NOT_SPECIFIED)->get('user_id')->target_id, "$entity_type: The entity author defaults to the default language.");
     $field = $entity->get('name');
-    $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name can be retrieved without specifying a language.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($default_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expect langcode.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($uid, $entity->get('user_id')->target_id, format_string('%entity_type: The entity author can be retrieved without specifying a language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($name, $field->value, "$entity_type: The entity name can be retrieved without specifying a language.");
+    $this->assertEqual($default_langcode, $field->getLangcode(), "$entity_type: The field object has the expect langcode.");
+    $this->assertEqual($uid, $entity->get('user_id')->target_id, "$entity_type: The entity author can be retrieved without specifying a language.");
 
     // Create property translations.
     $properties = array();
@@ -221,15 +221,11 @@ protected function doTestMultilingualProperties($entity_type) {
     // Check that property translation were correctly stored.
     $entity = entity_load($entity_type, $entity->id());
     foreach ($this->langcodes as $langcode) {
-      $args = array(
-        '%entity_type' => $entity_type,
-        '%langcode' => $langcode,
-      );
       $field = $entity->getTranslation($langcode)->get('name');
-      $this->assertEqual($properties[$langcode]['name'][0], $field->value, format_string('%entity_type: The entity name has been correctly stored for language %langcode.', $args));
+      $this->assertEqual($properties[$langcode]['name'][0], $field->value, "$entity_type: The entity name has been correctly stored for language $langcode.");
       $field_langcode = ($langcode == $entity->language()->getId()) ? $default_langcode : $langcode;
-      $this->assertEqual($field_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expected langcode  %langcode.', $args));
-      $this->assertEqual($properties[$langcode]['user_id'][0], $entity->getTranslation($langcode)->get('user_id')->target_id, format_string('%entity_type: The entity author has been correctly stored for language %langcode.', $args));
+      $this->assertEqual($field_langcode, $field->getLangcode(), "$entity_type: The field object has the expected langcode  $langcode.");
+      $this->assertEqual($properties[$langcode]['user_id'][0], $entity->getTranslation($langcode)->get('user_id')->target_id, "$entity_type: The entity author has been correctly stored for language $langcode.");
     }
 
     // Test query conditions (cache is reset at each call).
@@ -244,24 +240,24 @@ protected function doTestMultilingualProperties($entity_type) {
     ))->save();
 
     $entities = entity_load_multiple($entity_type);
-    $this->assertEqual(count($entities), 3, format_string('%entity_type: Three entities were created.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 3, "$entity_type: Three entities were created.");
     $entities = entity_load_multiple($entity_type, array($translated_id));
-    $this->assertEqual(count($entities), 1, format_string('%entity_type: One entity correctly loaded by id.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 1, "$entity_type: One entity correctly loaded by id.");
     $entities = entity_load_multiple_by_properties($entity_type, array('name' => $name));
-    $this->assertEqual(count($entities), 2, format_string('%entity_type: Two entities correctly loaded by name.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 2, "$entity_type: Two entities correctly loaded by name.");
     // @todo The default language condition should go away in favor of an
     // explicit parameter.
     $entities = entity_load_multiple_by_properties($entity_type, array('name' => $properties[$langcode]['name'][0], $default_langcode_key => 0));
-    $this->assertEqual(count($entities), 1, format_string('%entity_type: One entity correctly loaded by name translation.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 1, "$entity_type: One entity correctly loaded by name translation.");
     $entities = entity_load_multiple_by_properties($entity_type, array($langcode_key => $default_langcode, 'name' => $name));
-    $this->assertEqual(count($entities), 1, format_string('%entity_type: One entity correctly loaded by name and language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 1, "$entity_type: One entity correctly loaded by name and language.");
 
     $entities = entity_load_multiple_by_properties($entity_type, array($langcode_key => $langcode, 'name' => $properties[$langcode]['name'][0]));
-    $this->assertEqual(count($entities), 0, format_string('%entity_type: No entity loaded by name translation specifying the translation language.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 0, "$entity_type: No entity loaded by name translation specifying the translation language.");
     $entities = entity_load_multiple_by_properties($entity_type, array($langcode_key => $langcode, 'name' => $properties[$langcode]['name'][0], $default_langcode_key => 0));
-    $this->assertEqual(count($entities), 1, format_string('%entity_type: One entity loaded by name translation and language specifying to look for translations.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 1, "$entity_type: One entity loaded by name translation and language specifying to look for translations.");
     $entities = entity_load_multiple_by_properties($entity_type, array('user_id' => $properties[$langcode]['user_id'][0], $default_langcode_key => NULL));
-    $this->assertEqual(count($entities), 2, format_string('%entity_type: Two entities loaded by uid without caring about property translatability.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($entities), 2, "$entity_type: Two entities loaded by uid without caring about property translatability.");
 
     // Test property conditions and orders with multiple languages in the same
     // query.
@@ -273,7 +269,7 @@ protected function doTestMultilingualProperties($entity_type) {
       ->condition($group)
       ->condition('name', $properties[$langcode]['name'][0], '=', $langcode)
       ->execute();
-    $this->assertEqual(count($result), 1, format_string('%entity_type: One entity loaded by name and uid using different language meta conditions.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($result), 1, "$entity_type: One entity loaded by name and uid using different language meta conditions.");
 
     // Test mixed property and field conditions.
     $entity = entity_load($entity_type, reset($result), TRUE);
@@ -292,7 +288,7 @@ protected function doTestMultilingualProperties($entity_type) {
       ->condition($default_langcode_group)
       ->condition($langcode_group)
       ->execute();
-    $this->assertEqual(count($result), 1, format_string('%entity_type: One entity loaded by name, uid and field value using different language meta conditions.', array('%entity_type' => $entity_type)));
+    $this->assertEqual(count($result), 1, "$entity_type: One entity loaded by name, uid and field value using different language meta conditions.");
   }
 
   /**
@@ -431,7 +427,7 @@ protected function doTestEntityTranslationAPI($entity_type) {
     $translation = $entity->getTranslation($langcode2);
     $entity->removeTranslation($langcode2);
     foreach (array('get', 'set', '__get', '__set', 'createDuplicate') as $method) {
-      $message = format_string('The @method method raises an exception when trying to manipulate a removed translation.', array('@method' => $method));
+      $message = "The $method method raises an exception when trying to manipulate a removed translation.";
       try {
         $translation->{$method}('name', $this->randomMachineName());
         $this->fail($message);
@@ -453,7 +449,7 @@ protected function doTestEntityTranslationAPI($entity_type) {
     // Check that removing an invalid translation causes an exception to be
     // thrown.
     foreach (array($default_langcode, LanguageInterface::LANGCODE_DEFAULT, $this->randomMachineName()) as $invalid_langcode) {
-      $message = format_string('Removing an invalid translation (@langcode) causes an exception to be thrown.', array('@langcode' => $invalid_langcode));
+      $message = "Removing an invalid translation ($invalid_langcode) causes an exception to be thrown.";
       try {
         $entity->removeTranslation($invalid_langcode);
         $this->fail($message);
@@ -671,7 +667,7 @@ function testFieldDefinitions() {
     foreach ($translatable_fields as $name => $translatable) {
       $this->state->set('entity_test.field_definitions.translatable', array($name => $translatable));
       $this->entityManager->clearCachedFieldDefinitions();
-      $message = format_string('Field %field cannot be translatable.', array('%field' => $name));
+      $message = "Field $name cannot be translatable.";
 
       try {
         $this->entityManager->getBaseFieldDefinitions($entity_type);
@@ -765,7 +761,7 @@ function testEntityAdapter() {
     foreach ($langcodes as $langcode) {
       $adapter = $entity->getTranslation($langcode)->getTypedData();
       $name = $adapter->get('name')->value;
-      $this->assertEqual($name, $values[$langcode]['name'], SafeMarkup::format('Name correctly retrieved from "@langcode" adapter', array('@langcode' => $langcode)));
+      $this->assertEqual($name, $values[$langcode]['name'], 'Name correctly retrieved from "' . $langcode . '" adapter');
     }
   }
 
@@ -787,12 +783,10 @@ public function testFieldEntityReference() {
       $translation = $entity->getTranslation($langcode);
       foreach ($translation->getFields() as $field_name => $field) {
         if ($field->getFieldDefinition()->isTranslatable()) {
-          $args = ['%field_name' => $field_name, '%langcode' => $langcode];
-          $this->assertEqual($langcode, $field->getEntity()->language()->getId(), format_string('Translatable field %field_name on translation %langcode has correct entity reference in translation %langcode.', $args));
+          $this->assertEqual($langcode, $field->getEntity()->language()->getId(), "Translatable field $field_name on translation $langcode has correct entity reference in translation $langcode.");
         }
         else {
-          $args = ['%field_name' => $field_name, '%langcode' => $langcode, '%default_langcode' => $default_langcode];
-          $this->assertEqual($default_langcode, $field->getEntity()->language()->getId(), format_string('Non translatable field %field_name on translation %langcode has correct entity reference in the default translation %default_langcode.', $args));
+          $this->assertEqual($default_langcode, $field->getEntity()->language()->getId(), "Non translatable field $field_name on translation $langcode has correct entity reference in the default translation $default_langcode.");
         }
       }
     }
diff --git a/core/modules/user/src/Tests/UserRegistrationTest.php b/core/modules/user/src/Tests/UserRegistrationTest.php
index 1e16bc7..815b95e 100644
--- a/core/modules/user/src/Tests/UserRegistrationTest.php
+++ b/core/modules/user/src/Tests/UserRegistrationTest.php
@@ -276,7 +276,7 @@ public function testUniqueFields() {
 
     $edit = ['mail' => 'test@example.com', 'name' => $account->getUsername()];
     $this->drupalPostForm('user/register', $edit, t('Create new account'));
-    $this->assertRaw(SafeMarkup::format('The username %value is already taken.', ['%value' => $account->getUsername()]));
+    $this->assertRaw('The username <em class="placeholder">' . $account->getUsername() . '</em> is already taken.');
 
     $edit = ['mail' => $account->getEmail(), 'name' => $this->randomString()];
     $this->drupalPostForm('user/register', $edit, t('Create new account'));
diff --git a/core/modules/views/src/Tests/Handler/FieldKernelTest.php b/core/modules/views/src/Tests/Handler/FieldKernelTest.php
index b1897cd..8349d13 100644
--- a/core/modules/views/src/Tests/Handler/FieldKernelTest.php
+++ b/core/modules/views/src/Tests/Handler/FieldKernelTest.php
@@ -105,8 +105,8 @@ public function testQuery() {
    *   The value to search for.
    * @param string $message
    *   (optional) A message to display with the assertion. Do not translate
-   *   messages: use format_string() to embed variables in the message text, not
-   *   t(). If left blank, a default message will be displayed.
+   *   messages: just concatenate strings to embed variables in the message text
+   *   ,not t(). If left blank, a default message will be displayed.
    * @param string $group
    *   (optional) The group this message is in, which is displayed in a column
    *   in test output. Use 'Debug' to indicate this is debugging output. Do not
@@ -129,8 +129,8 @@ protected function assertSubString($haystack, $needle, $message = '', $group = '
    *   The value to search for.
    * @param string $message
    *   (optional) A message to display with the assertion. Do not translate
-   *   messages: use format_string() to embed variables in the message text, not
-   *   t(). If left blank, a default message will be displayed.
+   *   messages: just concatenate strings to embed variables in the message text
+   *   ,not t(). If left blank, a default message will be displayed.
    * @param string $group
    *   (optional) The group this message is in, which is displayed in a column
    *   in test output. Use 'Debug' to indicate this is debugging output. Do not