diff --git a/core/modules/field/src/Tests/FieldCrudTest.php b/core/modules/field/src/Tests/FieldCrudTest.php
index 5dd60e3..dbab583 100644
--- a/core/modules/field/src/Tests/FieldCrudTest.php
+++ b/core/modules/field/src/Tests/FieldCrudTest.php
@@ -118,20 +118,20 @@ function testCreateField() {
     // Guarantee that the field/bundle combination is unique.
     try {
       entity_create('field_config', $this->fieldDefinition)->save();
-      $this->fail(t('Cannot create two fields with the same field / bundle combination.'));
+      $this->fail('Cannot create two fields with the same field / bundle combination.');
     }
     catch (EntityStorageException $e) {
-      $this->pass(t('Cannot create two fields with the same field / bundle combination.'));
+      $this->pass('Cannot create two fields with the same field / bundle combination.');
     }
 
     // Check that the specified field exists.
     try {
       $this->fieldDefinition['field_name'] = $this->randomMachineName();
       entity_create('field_config', $this->fieldDefinition)->save();
-      $this->fail(t('Cannot create a field with a non-existing storage.'));
+      $this->fail('Cannot create a field with a non-existing storage.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field with a non-existing storage.'));
+      $this->pass('Cannot create a field with a non-existing storage.');
     }
 
     // TODO: test other failures.
diff --git a/core/modules/field/src/Tests/FieldStorageCrudTest.php b/core/modules/field/src/Tests/FieldStorageCrudTest.php
index 8912783..b74c738 100644
--- a/core/modules/field/src/Tests/FieldStorageCrudTest.php
+++ b/core/modules/field/src/Tests/FieldStorageCrudTest.php
@@ -82,10 +82,10 @@ function testCreate() {
     // Guarantee that the name is unique.
     try {
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create two fields with the same name.'));
+      $this->fail('Cannot create two fields with the same name.');
     }
     catch (EntityStorageException $e) {
-      $this->pass(t('Cannot create two fields with the same name.'));
+      $this->pass('Cannot create two fields with the same name.');
     }
 
     // Check that field type is required.
@@ -95,10 +95,10 @@ function testCreate() {
         'entity_type' => 'entity_type',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create a field with no type.'));
+      $this->fail('Cannot create a field with no type.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field with no type.'));
+      $this->pass('Cannot create a field with no type.');
     }
 
     // Check that field name is required.
@@ -108,10 +108,10 @@ function testCreate() {
         'entity_type' => 'entity_test',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create an unnamed field.'));
+      $this->fail('Cannot create an unnamed field.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create an unnamed field.'));
+      $this->pass('Cannot create an unnamed field.');
     }
     // Check that entity type is required.
     try {
@@ -134,10 +134,10 @@ function testCreate() {
         'type' => 'test_field',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create a field with a name starting with a digit.'));
+      $this->fail('Cannot create a field with a name starting with a digit.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field with a name starting with a digit.'));
+      $this->pass('Cannot create a field with a name starting with a digit.');
     }
 
     // Check that field name must only contain lowercase alphanumeric or _.
@@ -148,10 +148,10 @@ function testCreate() {
         'type' => 'test_field',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create a field with a name containing an illegal character.'));
+      $this->fail('Cannot create a field with a name containing an illegal character.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field with a name containing an illegal character.'));
+      $this->pass('Cannot create a field with a name containing an illegal character.');
     }
 
     // Check that field name cannot be longer than 32 characters long.
@@ -162,10 +162,10 @@ function testCreate() {
         'type' => 'test_field',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create a field with a name longer than 32 characters.'));
+      $this->fail('Cannot create a field with a name longer than 32 characters.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field with a name longer than 32 characters.'));
+      $this->pass('Cannot create a field with a name longer than 32 characters.');
     }
 
     // Check that field name can not be an entity key.
@@ -177,10 +177,10 @@ function testCreate() {
         'entity_type' => 'entity_test',
       );
       entity_create('field_storage_config', $field_storage_definition)->save();
-      $this->fail(t('Cannot create a field bearing the name of an entity key.'));
+      $this->fail('Cannot create a field bearing the name of an entity key.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot create a field bearing the name of an entity key.'));
+      $this->pass('Cannot create a field bearing the name of an entity key.');
     }
   }
 
@@ -378,10 +378,10 @@ function testUpdateFieldType() {
     try {
       $field_storage->set('type', 'integer');
       $field_storage->save();
-      $this->fail(t('Cannot update a field to a different type.'));
+      $this->fail('Cannot update a field to a different type.');
     }
     catch (FieldException $e) {
-      $this->pass(t('Cannot update a field to a different type.'));
+      $this->pass('Cannot update a field to a different type.');
     }
   }
 
@@ -443,18 +443,18 @@ function testUpdateForbid() {
     $field_storage->setSetting('changeable', $field_storage->getSetting('changeable') + 1);
     try {
       $field_storage->save();
-      $this->pass(t("A changeable setting can be updated."));
+      $this->pass('A changeable setting can be updated.');
     }
     catch (FieldStorageDefinitionUpdateForbiddenException $e) {
-      $this->fail(t("An unchangeable setting cannot be updated."));
+      $this->fail('An unchangeable setting cannot be updated.');
     }
     $field_storage->setSetting('unchangeable', $field_storage->getSetting('unchangeable') + 1);
     try {
       $field_storage->save();
-      $this->fail(t("An unchangeable setting can be updated."));
+      $this->fail('An unchangeable setting can be updated.');
     }
     catch (FieldStorageDefinitionUpdateForbiddenException $e) {
-      $this->pass(t("An unchangeable setting cannot be updated."));
+      $this->pass('An unchangeable setting cannot be updated.');
     }
   }
 
diff --git a/core/modules/node/src/Tests/NodeCreationTest.php b/core/modules/node/src/Tests/NodeCreationTest.php
index 7972f5d..f904ca3 100644
--- a/core/modules/node/src/Tests/NodeCreationTest.php
+++ b/core/modules/node/src/Tests/NodeCreationTest.php
@@ -91,10 +91,10 @@ function testFailedPageCreation() {
       // An exception is generated by node_test_exception_node_insert() if the
       // title is 'testing_transaction_exception'.
       entity_create('node', $edit)->save();
-      $this->fail(t('Expected exception has not been thrown.'));
+      $this->fail('Expected exception has not been thrown.');
     }
     catch (\Exception $e) {
-      $this->pass(t('Expected exception has been thrown.'));
+      $this->pass('Expected exception has been thrown.');
     }
 
     if (Database::getConnection()->supportsTransactions()) {
diff --git a/core/modules/node/src/Tests/NodeQueryAlterTest.php b/core/modules/node/src/Tests/NodeQueryAlterTest.php
index d0d615e..6612a42 100644
--- a/core/modules/node/src/Tests/NodeQueryAlterTest.php
+++ b/core/modules/node/src/Tests/NodeQueryAlterTest.php
@@ -68,7 +68,7 @@ function testNodeQueryAlterLowLevelWithAccess() {
       $this->assertEqual(count($result), 4, 'User with access can see correct nodes');
     }
     catch (\Exception $e) {
-      $this->fail(t('Altered query is malformed'));
+      $this->fail('Altered query is malformed');
     }
   }
 
@@ -91,7 +91,7 @@ function testNodeQueryAlterLowLevelNoAccess() {
       $this->assertEqual(count($result), 0, 'User with no access cannot see nodes');
     }
     catch (\Exception $e) {
-      $this->fail(t('Altered query is malformed'));
+      $this->fail('Altered query is malformed');
     }
   }
 
@@ -116,7 +116,7 @@ function testNodeQueryAlterLowLevelEditAccess() {
     catch (\Exception $e) {
       $this->fail($e->getMessage());
       $this->fail((string) $query);
-      $this->fail(t('Altered query is malformed'));
+      $this->fail('Altered query is malformed');
     }
   }
 
@@ -154,7 +154,7 @@ function testNodeQueryAlterOverride() {
       $this->assertEqual(count($result), 0, 'User view privileges are not overridden');
     }
     catch (\Exception $e) {
-      $this->fail(t('Altered query is malformed'));
+      $this->fail('Altered query is malformed');
     }
 
     // Have node_test_node_grants return a node_access_all privilege,
@@ -176,7 +176,7 @@ function testNodeQueryAlterOverride() {
       $this->assertEqual(count($result), 4, 'User view privileges are overridden');
     }
     catch (\Exception $e) {
-      $this->fail(t('Altered query is malformed'));
+      $this->fail('Altered query is malformed');
     }
     \Drupal::state()->delete('node_access_test.no_access_uid');
   }
diff --git a/core/modules/options/src/Tests/OptionsFieldTest.php b/core/modules/options/src/Tests/OptionsFieldTest.php
index 0380ec0..5cee377 100644
--- a/core/modules/options/src/Tests/OptionsFieldTest.php
+++ b/core/modules/options/src/Tests/OptionsFieldTest.php
@@ -42,10 +42,10 @@ function testUpdateAllowedValues() {
     $this->fieldStorage->setSetting('allowed_values', [2 => 'Two']);
     try {
       $this->fieldStorage->save();
-      $this->fail(t('Cannot update a list field storage to not include keys with existing data.'));
+      $this->fail('Cannot update a list field storage to not include keys with existing data.');
     }
     catch (FieldStorageDefinitionUpdateForbiddenException $e) {
-      $this->pass(t('Cannot update a list field storage to not include keys with existing data.'));
+      $this->pass('Cannot update a list field storage to not include keys with existing data.');
     }
     // Empty the value, so that we can actually remove the option.
     unset($entity->{$this->fieldName});
diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index 1f97845..c815f94 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -8,6 +8,7 @@
 namespace Drupal\simpletest\Tests;
 
 use Drupal\Component\Utility\Crypt;
+use Drupal\Component\Utility\SafeMarkup;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -189,7 +190,7 @@ function stubTest() {
 
     // This causes the tenth of the fifteen passes asserted in
     // confirmStubResults().
-    $this->pass(t('Test ID is @id.', array('@id' => $this->testId)));
+    $this->pass('Test ID is ' . $this->testId . '.');
 
     // These cause the eleventh to fourteenth of the fifteen passes asserted in
     // confirmStubResults().
@@ -218,7 +219,7 @@ function stubTest() {
    * Assert nothing.
    */
   function assertNothing() {
-    $this->pass("This is nothing.");
+    $this->pass('This is nothing.');
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Database/TransactionTest.php b/core/modules/system/src/Tests/Database/TransactionTest.php
index 1137b21..48e5183 100644
--- a/core/modules/system/src/Tests/Database/TransactionTest.php
+++ b/core/modules/system/src/Tests/Database/TransactionTest.php
@@ -302,7 +302,7 @@ function testTransactionWithDdlStatement() {
         unset($transaction);
         // @TODO: an exception should be triggered here, but is not, because
         // "ROLLBACK" fails silently in MySQL if there is no transaction active.
-        // $this->fail(t('Rolling back a transaction containing DDL should fail.'));
+        // $this->fail('Rolling back a transaction containing DDL should fail.');
       }
       catch (TransactionNoActiveException $e) {
         $this->pass('Rolling back a transaction containing DDL should fail.');
diff --git a/core/modules/system/src/Tests/Entity/FieldSqlStorageTest.php b/core/modules/system/src/Tests/Entity/FieldSqlStorageTest.php
index 549c17a..dcc163d 100644
--- a/core/modules/system/src/Tests/Entity/FieldSqlStorageTest.php
+++ b/core/modules/system/src/Tests/Entity/FieldSqlStorageTest.php
@@ -335,10 +335,10 @@ function testUpdateFieldSchemaWithData() {
     $field_storage->setSetting('scale', 3);
     try {
       $field_storage->save();
-      $this->fail(t('Cannot update field schema with data.'));
+      $this->fail('Cannot update field schema with data.');
     }
     catch (FieldStorageDefinitionUpdateForbiddenException $e) {
-      $this->pass(t('Cannot update field schema with data.'));
+      $this->pass('Cannot update field schema with data.');
     }
   }
 
@@ -364,10 +364,10 @@ function testFieldUpdateFailure() {
     $field_storage->setSetting('max_length', '-1)');
     try {
       $field_storage->save();
-      $this->fail(t('Update succeeded.'));
+      $this->fail('Update succeeded.');
     }
     catch (\Exception $e) {
-      $this->pass(t('Update properly failed.'));
+      $this->pass('Update properly failed.');
     }
 
     // Ensure that the field tables are still there.
diff --git a/core/modules/system/src/Tests/Routing/MatcherDumperTest.php b/core/modules/system/src/Tests/Routing/MatcherDumperTest.php
index f98d294..8cb53b3 100644
--- a/core/modules/system/src/Tests/Routing/MatcherDumperTest.php
+++ b/core/modules/system/src/Tests/Routing/MatcherDumperTest.php
@@ -103,7 +103,7 @@ function testAddAdditionalRoutes() {
     foreach ($collection_routes as $name => $route) {
       if (empty($dumper_routes[$name])) {
         $success = FALSE;
-        $this->fail(t('Not all routes found in the dumper.'));
+        $this->fail('Not all routes found in the dumper.');
       }
     }
 
diff --git a/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php b/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
index 3ca3872..ceb439d 100644
--- a/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
+++ b/core/modules/system/tests/src/Kernel/Extension/ModuleHandlerTest.php
@@ -118,10 +118,10 @@ function testDependencyResolution() {
 
     try {
       $result = $this->moduleInstaller()->install(array('color'));
-      $this->fail(t('ModuleInstaller::install() throws an exception if dependencies are missing.'));
+      $this->fail('ModuleInstaller::install() throws an exception if dependencies are missing.');
     }
     catch (\Drupal\Core\Extension\MissingDependencyException $e) {
-      $this->pass(t('ModuleInstaller::install() throws an exception if dependencies are missing.'));
+      $this->pass('ModuleInstaller::install() throws an exception if dependencies are missing.');
     }
 
     $this->assertFalse($this->moduleHandler()->moduleExists('color'), 'ModuleHandler::install() aborts if dependencies are missing.');