diff --git a/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
index 6dfc66c..3e23175 100644
--- a/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockStorageUnitTest.php
@@ -114,7 +114,7 @@ protected function loadTests() {
     $this->assertEqual($entity->getRegion(), '-1');
     $this->assertTrue($entity->status());
     $this->assertEqual($entity->getTheme(), 'stark');
-    $this->assertTrue($entity->uuid());
+    $this->assertNotEmpty($entity->uuid());
   }
 
   /**
diff --git a/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
index 64b2109..34f7922 100644
--- a/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
+++ b/core/modules/block/tests/src/Kernel/BlockViewBuilderTest.php
@@ -155,7 +155,7 @@ protected function verifyRenderCacheHandling() {
     $build = $this->getBlockRenderArray();
     $cid = 'entity_view:block:test_block:' . implode(':', \Drupal::service('cache_contexts_manager')->convertTokensToKeys(['languages:' . LanguageInterface::TYPE_INTERFACE, 'theme', 'user.permissions'])->getKeys());
     $this->renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
 
     // Re-save the block and check that the cache entry has been deleted.
     $this->block->save();
@@ -169,7 +169,7 @@ protected function verifyRenderCacheHandling() {
     $build['#block'] = $this->block;
 
     $this->renderer->renderRoot($build);
-    $this->assertTrue($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
+    $this->assertNotEmpty($this->container->get('cache.render')->get($cid), 'The block render element has been cached.');
     $this->block->delete();
     $this->assertFalse($this->container->get('cache.render')->get($cid), 'The block render cache entry has been cleared when the block was deleted.');
 
@@ -306,7 +306,7 @@ protected function assertBlockRenderedWithExpectedCacheability(array $expected_k
     $final_cache_contexts = Cache::mergeContexts($expected_contexts, $required_cache_contexts);
     $cid = implode(':', $expected_keys) . ':' . implode(':', \Drupal::service('cache_contexts_manager')->convertTokensToKeys($final_cache_contexts)->getKeys());
     $cache_item = $this->container->get('cache.render')->get($cid);
-    $this->assertTrue($cache_item, 'The block render element has been cached with the expected cache ID.');
+    $this->assertNotEmpty($cache_item, 'The block render element has been cached with the expected cache ID.');
     $this->assertIdentical(Cache::mergeTags($expected_tags, ['rendered']), $cache_item->tags);
     $this->assertIdentical($final_cache_contexts, $cache_item->data['#cache']['contexts']);
     $this->assertIdentical($expected_tags, $cache_item->data['#cache']['tags']);
diff --git a/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentFieldInstanceTest.php b/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentFieldInstanceTest.php
index c7d8959..281d6fd 100644
--- a/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentFieldInstanceTest.php
+++ b/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentFieldInstanceTest.php
@@ -60,7 +60,7 @@ protected function assertEntity($id, $field_name, $bundle, $default_mode, $per_p
     $this->assertTrue($entity->isRequired());
     $this->assertIdentical($field_name, $entity->getFieldStorageDefinition()->getName());
     $this->assertIdentical($bundle, $entity->getTargetBundle());
-    $this->assertTrue($entity->get('default_value')[0]['status']);
+    $this->assertEquals(1, $entity->get('default_value')[0]['status']);
     $this->assertEqual($default_mode, $entity->getSetting('default_mode'));
     $this->assertIdentical($per_page, $entity->getSetting('per_page'));
     $this->assertEqual($anonymous, $entity->getSetting('anonymous'));
diff --git a/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentTest.php b/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentTest.php
index ed19178..99d1372 100644
--- a/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentTest.php
+++ b/core/modules/comment/tests/src/Kernel/Migrate/d7/MigrateCommentTest.php
@@ -56,7 +56,7 @@ public function testCommentMigration() {
     $this->assertIdentical('A comment', $comment->getSubject());
     $this->assertIdentical('1421727536', $comment->getCreatedTime());
     $this->assertIdentical('1421727536', $comment->getChangedTime());
-    $this->assertTrue($comment->getStatus());
+    $this->assertEquals(1, $comment->getStatus());
     $this->assertIdentical('admin', $comment->getAuthorName());
     $this->assertIdentical('admin@local.host', $comment->getAuthorEmail());
     $this->assertIdentical('This is a comment', $comment->comment_body->value);
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
index ffb91b0..e4e7a0a 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
@@ -72,7 +72,7 @@ public function testLinkApprove() {
 
     // Check if I can see the comment approve link on an approved comment.
     $approve_comment = $view->style_plugin->getField(1, 'approve_comment');
-    $this->assertFalse((string) $approve_comment, "Didn't find a comment approve link for an already approved comment.");
+    $this->assertEmpty((string) $approve_comment, "Didn't find a comment approve link for an already approved comment.");
 
     // Check if I can see the comment approve link on an approved comment as an
     // anonymous user.
@@ -84,7 +84,7 @@ public function testLinkApprove() {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'approve_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't approve the comment as an anonymous user.");
+    $this->assertEmpty((string) $replyto_comment, "I can't approve the comment as an anonymous user.");
   }
 
   /**
@@ -147,7 +147,7 @@ public function testLinkReply() {
 
     // Check if I can see the reply link on an unapproved comment.
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "I can't reply to an unapproved comment.");
+    $this->assertEmpty((string) $replyto_comment, "I can't reply to an unapproved comment.");
 
     // Approve the comment.
     $comment->setPublished(CommentInterface::PUBLISHED);
@@ -170,7 +170,7 @@ public function testLinkReply() {
     $view = Views::getView('test_comment');
     $view->preview();
     $replyto_comment = $view->style_plugin->getField(0, 'replyto_comment');
-    $this->assertFalse((string) $replyto_comment, "Didn't find the comment reply link as an anonymous user.");
+    $this->assertEmpty((string) $replyto_comment, "Didn't find the comment reply link as an anonymous user.");
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/BulkDeleteTest.php b/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
index 41fedfc..4053caf 100644
--- a/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
+++ b/core/modules/field/tests/src/Kernel/BulkDeleteTest.php
@@ -197,7 +197,7 @@ function testDeleteField() {
       ->condition('type', $bundle)
       ->condition("$field_name.deleted", 0)
       ->execute();
-    $this->assertFalse($found, 'No entities found after deleting');
+    $this->assertEmpty($found, 'No entities found after deleting');
 
     // There are 10 entities of this bundle when deleted fields are allowed, and
     // their values are correct.
@@ -207,7 +207,7 @@ function testDeleteField() {
       ->sort('id')
       ->execute();
     $this->assertEqual(count($found), 10, 'Correct number of entities found after deleting');
-    $this->assertFalse(array_diff($found, array_keys($this->entities)));
+    $this->assertEmpty(array_diff($found, array_keys($this->entities)));
   }
 
   /**
diff --git a/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php b/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
index 8237ef4..afbdf04 100644
--- a/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldAttachStorageTest.php
@@ -277,9 +277,9 @@ function testFieldAttachDelete() {
     $controller->resetCache();
     foreach (array(0, 1, 2) as $vid) {
       $revision = $controller->loadRevision($vid);
-      $this->assertFalse($revision);
+      $this->assertNull($revision);
     }
-    $this->assertFalse($controller->load($entity->id()));
+    $this->assertNull($controller->load($entity->id()));
   }
 
   /**
@@ -369,8 +369,8 @@ function testEntityDeleteBundle() {
     $this->assertTrue(empty($entity->{$field_name}), 'No data for second field');
 
     // Verify that the fields are gone.
-    $this->assertFalse(FieldConfig::load('entity_test.' . $this->fieldTestData->field->getTargetBundle() . '.' . $this->fieldTestData->field_name), "First field is deleted");
-    $this->assertFalse(FieldConfig::load('entity_test.' . $field['bundle'] . '.' . $field_name), "Second field is deleted");
+    $this->assertNull(FieldConfig::load('entity_test.' . $this->fieldTestData->field->getTargetBundle() . '.' . $this->fieldTestData->field_name), "First field is deleted");
+    $this->assertNull(FieldConfig::load('entity_test.' . $field['bundle'] . '.' . $field_name), "Second field is deleted");
   }
 
 }
diff --git a/core/modules/field/tests/src/Kernel/FieldCrudTest.php b/core/modules/field/tests/src/Kernel/FieldCrudTest.php
index a61d645..5f75cba 100644
--- a/core/modules/field/tests/src/Kernel/FieldCrudTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldCrudTest.php
@@ -72,7 +72,7 @@ function testCreateField() {
     $field->save();
 
     $field = FieldConfig::load($field->id());
-    $this->assertTrue($field->getSetting('field_setting_from_config_data'));
+    $this->assertEquals('TRUE', $field->getSetting('field_setting_from_config_data'));
     $this->assertNull($field->getSetting('config_data_from_field_setting'));
 
     // Read the configuration. Check against raw configuration data rather than
@@ -253,8 +253,8 @@ function testDeleteFieldCrossDeletion() {
     FieldConfig::create($this->fieldDefinition)->save();
     FieldConfig::create($field_definition_2)->save();
     $field_storage->delete();
-    $this->assertFalse(FieldConfig::loadByName('entity_test', $this->fieldDefinition['bundle'], $field_storage->getName()));
-    $this->assertFalse(FieldConfig::loadByName('entity_test', $field_definition_2['bundle'], $field_storage->getName()));
+    $this->assertNull(FieldConfig::loadByName('entity_test', $this->fieldDefinition['bundle'], $field_storage->getName()));
+    $this->assertNull(FieldConfig::loadByName('entity_test', $field_definition_2['bundle'], $field_storage->getName()));
 
     // Check that deletion of the last field deletes the storage.
     $field_storage = FieldStorageConfig::create($this->fieldStorageDefinition);
@@ -264,9 +264,9 @@ function testDeleteFieldCrossDeletion() {
     $field_2 = FieldConfig::create($field_definition_2);
     $field_2->save();
     $field->delete();
-    $this->assertTrue(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNotEmpty(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
     $field_2->delete();
-    $this->assertFalse(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNull(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
 
     // Check that deletion of all fields using a storage simultaneously deletes
     // the storage.
@@ -277,7 +277,7 @@ function testDeleteFieldCrossDeletion() {
     $field_2 = FieldConfig::create($field_definition_2);
     $field_2->save();
     $this->container->get('entity.manager')->getStorage('field_config')->delete(array($field, $field_2));
-    $this->assertFalse(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
+    $this->assertNull(FieldStorageConfig::loadByName('entity_test', $field_storage->getName()));
   }
 
   /**
diff --git a/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php b/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
index 3478dd3..b276655 100644
--- a/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
+++ b/core/modules/field/tests/src/Kernel/FieldImportCreateTest.php
@@ -26,11 +26,11 @@ function testImportCreateDefault() {
     $field_id_2b = "entity_test.test_bundle.$field_name_2";
 
     // Check that the field storages and fields do not exist yet.
-    $this->assertFalse(FieldStorageConfig::load($field_storage_id));
-    $this->assertFalse(FieldConfig::load($field_id));
-    $this->assertFalse(FieldStorageConfig::load($field_storage_id_2));
-    $this->assertFalse(FieldConfig::load($field_id_2a));
-    $this->assertFalse(FieldConfig::load($field_id_2b));
+    $this->assertNull(FieldStorageConfig::load($field_storage_id));
+    $this->assertNull(FieldConfig::load($field_id));
+    $this->assertNull(FieldStorageConfig::load($field_storage_id_2));
+    $this->assertNull(FieldConfig::load($field_id_2a));
+    $this->assertNull(FieldConfig::load($field_id_2b));
 
     // Create a second bundle for the 'Entity test' entity type.
     entity_test_create_bundle('test_bundle');
@@ -41,15 +41,17 @@ function testImportCreateDefault() {
 
     // A field storage with one single field.
     $field_storage = FieldStorageConfig::load($field_storage_id);
-    $this->assertTrue($field_storage, 'The field was created.');
+    $this->assertNotEmpty($field_storage, 'The field was created.');
     $field = FieldConfig::load($field_id);
-    $this->assertTrue($field, 'The field was deleted.');
+    $this->assertNotEmpty($field, 'The field was deleted.');
 
     // A field storage with two fields.
     $field_storage_2 = FieldStorageConfig::load($field_storage_id_2);
-    $this->assertTrue($field_storage_2, 'The second field was created.');
-    $this->assertTrue($field->getTargetBundle(), 'test_bundle', 'The second field was created on bundle test_bundle.');
-    $this->assertTrue($field->getTargetBundle(), 'test_bundle_2', 'The second field was created on bundle test_bundle_2.');
+    $this->assertNotEmpty($field_storage_2, 'The second field was created.');
+    $field2a = FieldConfig::load($field_id_2a);
+    $this->assertEquals('entity_test', $field2a->getTargetBundle(), 'The second field was created on bundle entity_test.');
+    $field2b = FieldConfig::load($field_id_2b);
+    $this->assertEquals('test_bundle', $field2b->getTargetBundle(), 'The second field was created on bundle test_bundle.');
 
     // Tests fields.
     $ids = \Drupal::entityQuery('field_config')
@@ -94,26 +96,26 @@ function testImportCreate() {
     // Add the new files to the sync directory.
     $src_dir = __DIR__ . '/../../modules/field_test_config/sync';
     $target_dir = config_get_config_directory(CONFIG_SYNC_DIRECTORY);
-    $this->assertTrue(file_unmanaged_copy("$src_dir/$field_storage_config_name.yml", "$target_dir/$field_storage_config_name.yml"));
-    $this->assertTrue(file_unmanaged_copy("$src_dir/$field_config_name.yml", "$target_dir/$field_config_name.yml"));
-    $this->assertTrue(file_unmanaged_copy("$src_dir/$field_storage_config_name_2.yml", "$target_dir/$field_storage_config_name_2.yml"));
-    $this->assertTrue(file_unmanaged_copy("$src_dir/$field_config_name_2a.yml", "$target_dir/$field_config_name_2a.yml"));
-    $this->assertTrue(file_unmanaged_copy("$src_dir/$field_config_name_2b.yml", "$target_dir/$field_config_name_2b.yml"));
+    $this->assertNotEmpty(file_unmanaged_copy("$src_dir/$field_storage_config_name.yml", "$target_dir/$field_storage_config_name.yml"));
+    $this->assertNotEmpty(file_unmanaged_copy("$src_dir/$field_config_name.yml", "$target_dir/$field_config_name.yml"));
+    $this->assertNotEmpty(file_unmanaged_copy("$src_dir/$field_storage_config_name_2.yml", "$target_dir/$field_storage_config_name_2.yml"));
+    $this->assertNotEmpty(file_unmanaged_copy("$src_dir/$field_config_name_2a.yml", "$target_dir/$field_config_name_2a.yml"));
+    $this->assertNotEmpty(file_unmanaged_copy("$src_dir/$field_config_name_2b.yml", "$target_dir/$field_config_name_2b.yml"));
 
     // Import the content of the sync directory.
     $this->configImporter()->import();
 
     // Check that the field and storage were created.
     $field_storage = FieldStorageConfig::load($field_storage_id);
-    $this->assertTrue($field_storage, 'Test import storage field from sync exists');
+    $this->assertNotEmpty($field_storage, 'Test import storage field from sync exists');
     $field = FieldConfig::load($field_id);
-    $this->assertTrue($field, 'Test import field  from sync exists');
+    $this->assertNotEmpty($field, 'Test import field  from sync exists');
     $field_storage = FieldStorageConfig::load($field_storage_id_2);
-    $this->assertTrue($field_storage, 'Test import storage field 2 from sync exists');
+    $this->assertNotEmpty($field_storage, 'Test import storage field 2 from sync exists');
     $field = FieldConfig::load($field_id_2a);
-    $this->assertTrue($field, 'Test import field 2a from sync exists');
+    $this->assertNotEmpty($field, 'Test import field 2a from sync exists');
     $field = FieldConfig::load($field_id_2b);
-    $this->assertTrue($field, 'Test import field 2b from sync exists');
+    $this->assertNotEmpty($field, 'Test import field 2b from sync exists');
   }
 
 }
diff --git a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
index 3bf0028..adf7008 100644
--- a/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
+++ b/core/modules/migrate_drupal/src/Tests/StubTestTrait.php
@@ -18,7 +18,7 @@
    */
   protected function performStubTest($entity_type_id) {
     $entity_id = $this->createStub($entity_type_id);
-    $this->assertTrue($entity_id, 'Stub successfully created');
+    $this->assertNotEmpty($entity_id, 'Stub successfully created');
     if ($entity_id) {
       $violations = $this->validateStub($entity_type_id, $entity_id);
       if (!$this->assertIdentical(count($violations), 0, 'Stub is a valid entity')) {
diff --git a/core/modules/simpletest/src/UserCreationTrait.php b/core/modules/simpletest/src/UserCreationTrait.php
index de6d283..66c6fe4 100644
--- a/core/modules/simpletest/src/UserCreationTrait.php
+++ b/core/modules/simpletest/src/UserCreationTrait.php
@@ -70,7 +70,7 @@ protected function createUser(array $permissions = array(), $name = NULL, $admin
     $account = User::create($edit);
     $account->save();
 
-    $this->assertTrue($account->id(), SafeMarkup::format('User created with name %name and pass %pass', array('%name' => $edit['name'], '%pass' => $edit['pass'])), 'User login');
+    $this->assertNotNull($account->id(), SafeMarkup::format('User created with name %name and pass %pass', array('%name' => $edit['name'], '%pass' => $edit['pass'])), 'User login');
     if (!$account->id()) {
       return FALSE;
     }
diff --git a/core/tests/Drupal/KernelTests/AssertLegacyTrait.php b/core/tests/Drupal/KernelTests/AssertLegacyTrait.php
index 1d1816a..c089177 100644
--- a/core/tests/Drupal/KernelTests/AssertLegacyTrait.php
+++ b/core/tests/Drupal/KernelTests/AssertLegacyTrait.php
@@ -24,30 +24,6 @@ protected function assert($actual, $message = '') {
   }
 
   /**
-   * @see \Drupal\simpletest\TestBase::assertTrue()
-   */
-  public static function assertTrue($actual, $message = '') {
-    if (is_bool($actual)) {
-      parent::assertTrue($actual, $message);
-    }
-    else {
-      parent::assertNotEmpty($actual, $message);
-    }
-  }
-
-  /**
-   * @see \Drupal\simpletest\TestBase::assertFalse()
-   */
-  public static function assertFalse($actual, $message = '') {
-    if (is_bool($actual)) {
-      parent::assertFalse($actual, $message);
-    }
-    else {
-      parent::assertEmpty($actual, $message);
-    }
-  }
-
-  /**
    * @see \Drupal\simpletest\TestBase::assertEqual()
    *
    * @deprecated Scheduled for removal in Drupal 9.0.0. Use self::assertEquals()
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php b/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
index 72e7b6f..0fd3d10 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/AttachedAssetsTest.php
@@ -419,7 +419,7 @@ function testLibraryAlter() {
     $js = $this->assetResolver->getJsAssets($assets, FALSE)[1];
     $js_render_array = \Drupal::service('asset.js.collection_renderer')->render($js);
     $rendered_js = $this->renderer->renderPlain($js_render_array);
-    $this->assertTrue(strpos($rendered_js, 'core/assets/vendor/jquery-form/jquery.form.min.js'), 'Altered library dependencies are added to the page.');
+    $this->assertNotFalse(strpos($rendered_js, 'core/assets/vendor/jquery-form/jquery.form.min.js'), 'Altered library dependencies are added to the page.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
index a77adfc..2b7a5ff 100644
--- a/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Asset/LibraryDiscoveryIntegrationTest.php
@@ -37,7 +37,7 @@ public function testHookLibraryInfoByTheme() {
     // Activate test_theme and verify that the library 'kitten' is added using
     // hook_library_info_alter().
     $this->activateTheme('test_theme');
-    $this->assertTrue($this->libraryDiscovery->getLibraryByName('test_theme', 'kitten'));
+    $this->assertNotEmpty($this->libraryDiscovery->getLibraryByName('test_theme', 'kitten'));
 
     // Now make classy the active theme and assert that library is not added.
     $this->activateTheme('classy');
@@ -57,7 +57,7 @@ public function testLibrariesOverride() {
     $this->assertAssetInLibrary('core/themes/classy/css/components/dialog.css', 'classy', 'dialog', 'css');
 
     // Confirmatory assert on core library to be removed.
-    $this->assertTrue($this->libraryDiscovery->getLibraryByName('core', 'drupal.progress'), 'Confirmatory test on "core/drupal.progress"');
+    $this->assertNotEmpty($this->libraryDiscovery->getLibraryByName('core', 'drupal.progress'), 'Confirmatory test on "core/drupal.progress"');
 
     // Activate test theme that defines libraries overrides.
     $this->activateTheme('test_theme');
diff --git a/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php b/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
index 484ee9c..bec72fa 100644
--- a/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Cache/DatabaseBackendTagTest.php
@@ -40,7 +40,7 @@ public function testTagInvalidations() {
     foreach ($bins as $bin) {
       $bin = \Drupal::cache($bin);
       $bin->set('test', 'value', Cache::PERMANENT, $tags);
-      $this->assertTrue($bin->get('test'), 'Cache item was set in bin.');
+      $this->assertNotEmpty($bin->get('test'), 'Cache item was set in bin.');
     }
 
     $invalidations_before = intval(db_select('cachetags')->fields('cachetags', array('invalidations'))->condition('tag', 'test_tag:2')->execute()->fetchField());
diff --git a/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php b/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
index d5f3e95..9d82f23 100644
--- a/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
+++ b/core/tests/Drupal/KernelTests/Core/Cache/GenericCacheBackendUnitTestBase.php
@@ -465,7 +465,7 @@ public function testDeleteMultiple() {
     $this->assertIdentical(FALSE, $backend->get('test21'), "Cache id test21 does not exist.");
 
     // Calling deleteMultiple() with an empty array should not cause an error.
-    $this->assertFalse($backend->deleteMultiple(array()));
+    $this->assertNull($backend->deleteMultiple(array()));
   }
 
   /**
@@ -484,7 +484,7 @@ public function testDeleteAll() {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
     $this->assertFalse($backend_a->get('test2'), 'Second key has been deleted.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
   }
 
   /**
@@ -517,7 +517,7 @@ function testInvalidate() {
 
     // Calling invalidateMultiple() with an empty array should not cause an
     // error.
-    $this->assertFalse($backend->invalidateMultiple(array()));
+    $this->assertNull($backend->invalidateMultiple(array()));
   }
 
   /**
@@ -562,7 +562,7 @@ function testInvalidateTags() {
     $bins = array('path', 'bootstrap', 'page');
     foreach ($bins as $bin) {
       $this->getCacheBackend($bin)->set('test', $this->defaultValue, Cache::PERMANENT, $tags);
-      $this->assertTrue($this->getCacheBackend($bin)->get('test'), 'Cache item was set in bin.');
+      $this->assertNotEmpty($this->getCacheBackend($bin)->get('test'), 'Cache item was set in bin.');
     }
 
     Cache::invalidateTags(array('test_tag:2'));
@@ -574,7 +574,7 @@ function testInvalidateTags() {
     // Test that the cache entry with a matching tag has been invalidated.
     $this->assertFalse($this->getCacheBackend($bin)->get('test_cid_invalidate2'), 'Cache items matching tag were invalidated.');
     // Test that the cache entry with without a matching tag still exists.
-    $this->assertTrue($this->getCacheBackend($bin)->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
+    $this->assertNotEmpty($this->getCacheBackend($bin)->get('test_cid_invalidate1'), 'Cache items not matching tag were not invalidated.');
   }
 
   /**
@@ -593,9 +593,9 @@ public function testInvalidateAll() {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been invalidated.');
     $this->assertFalse($backend_a->get('test2'), 'Second key has been invalidated.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
-    $this->assertTrue($backend_a->get('test1', TRUE), 'First key has not been deleted.');
-    $this->assertTrue($backend_a->get('test2', TRUE), 'Second key has not been deleted.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_a->get('test1', TRUE), 'First key has not been deleted.');
+    $this->assertNotEmpty($backend_a->get('test2', TRUE), 'Second key has not been deleted.');
   }
 
   /**
@@ -614,7 +614,7 @@ public function testRemoveBin() {
 
     $this->assertFalse($backend_a->get('test1'), 'First key has been deleted.');
     $this->assertFalse($backend_a->get('test2', TRUE), 'Second key has been deleted.');
-    $this->assertTrue($backend_b->get('test3'), 'Item in other bin is preserved.');
+    $this->assertNotEmpty($backend_b->get('test3'), 'Item in other bin is preserved.');
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php b/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
index 7ff414c..df614e9 100644
--- a/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Command/DbDumpTest.php
@@ -156,21 +156,21 @@ public function testDbDumpCommand() {
 
     // Tables that are schema-only should not have data exported.
     $pattern = preg_quote("\$connection->insert('sessions')");
-    $this->assertFalse(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Tables defined as schema-only do not have data exported to the script.');
+    $this->assertNotRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Tables defined as schema-only do not have data exported to the script.');
 
     // Table data is exported.
     $pattern = preg_quote("\$connection->insert('config')");
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Table data is properly exported to the script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Table data is properly exported to the script.');
 
     // The test data are in the dump (serialized).
     $pattern = preg_quote(serialize($this->data));
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'Generated data is found in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'Generated data is found in the exported script.');
 
     // Check that the user account name and email address was properly escaped.
     $pattern = preg_quote('"q\'uote\$dollar@example.com"');
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'The user account email address was properly escaped in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'The user account email address was properly escaped in the exported script.');
     $pattern = preg_quote('\'$dollar\'');
-    $this->assertTrue(preg_match('/' . $pattern . '/', $command_tester->getDisplay()), 'The user account name was properly escaped in the exported script.');
+    $this->assertRegExp('/' . $pattern . '/', $command_tester->getDisplay(), 'The user account name was properly escaped in the exported script.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
index 2fd6301..6569147 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigDependencyTest.php
@@ -219,8 +219,8 @@ public function testConfigEntityUninstall() {
     // Test that doing a config uninstall of the node module deletes entity2
     // since it is dependent on entity1 which is dependent on the node module.
     $config_manager->uninstall('module', 'node');
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
-    $this->assertFalse($storage->load('entity2'), 'Entity 2 deleted');
+    $this->assertEmpty($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertEmpty($storage->load('entity2'), 'Entity 2 deleted');
 
     // Set a more complicated test where dependencies will be fixed.
     \Drupal::state()->set('config_test.fix_dependencies', array($entity1->getConfigDependencyName()));
@@ -299,14 +299,14 @@ public function testConfigEntityUninstall() {
     $config_manager->uninstall('module', 'node');
 
     // Test that expected actions have been performed.
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertEmpty($storage->load('entity1'), 'Entity 1 deleted');
     $entity2 = $storage->load('entity2');
-    $this->assertTrue($entity2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity2, 'Entity 2 not deleted');
     $this->assertEqual($entity2->calculateDependencies()->getDependencies()['config'], array(), 'Entity 2 dependencies updated to remove dependency on Entity1.');
     $entity3 = $storage->load('entity3');
-    $this->assertTrue($entity3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity3, 'Entity 3 not deleted');
     $this->assertEqual($entity3->calculateDependencies()->getDependencies()['config'], [$entity2->getConfigDependencyName()], 'Entity 3 still depends on Entity 2.');
-    $this->assertFalse($storage->load('entity4'), 'Entity 4 deleted');
+    $this->assertEmpty($storage->load('entity4'), 'Entity 4 deleted');
   }
 
   /**
@@ -346,8 +346,8 @@ public function testConfigEntityDelete() {
     // Test that doing a delete of entity1 deletes entity2 since it is dependent
     // on entity1.
     $entity1->delete();
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
-    $this->assertFalse($storage->load('entity2'), 'Entity 2 deleted');
+    $this->assertEmpty($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertEmpty($storage->load('entity2'), 'Entity 2 deleted');
 
     // Set a more complicated test where dependencies will be fixed.
     \Drupal::state()->set('config_test.fix_dependencies', array($entity1->getConfigDependencyName()));
@@ -400,12 +400,12 @@ public function testConfigEntityDelete() {
     $entity1->delete();
 
     // Test that expected actions have been performed.
-    $this->assertFalse($storage->load('entity1'), 'Entity 1 deleted');
+    $this->assertEmpty($storage->load('entity1'), 'Entity 1 deleted');
     $entity2 = $storage->load('entity2');
-    $this->assertTrue($entity2, 'Entity 2 not deleted');
+    $this->assertNotEmpty($entity2, 'Entity 2 not deleted');
     $this->assertEqual($entity2->calculateDependencies()->getDependencies()['config'], array(), 'Entity 2 dependencies updated to remove dependency on Entity1.');
     $entity3 = $storage->load('entity3');
-    $this->assertTrue($entity3, 'Entity 3 not deleted');
+    $this->assertNotEmpty($entity3, 'Entity 3 not deleted');
     $this->assertEqual($entity3->calculateDependencies()->getDependencies()['config'], [$entity2->getConfigDependencyName()], 'Entity 3 still depends on Entity 2.');
   }
 
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
index c440c03..1f6c8f6 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigFileContentTest.php
@@ -55,7 +55,7 @@ function testReadWriteConfig() {
 
     // Verify a configuration object is returned.
     $this->assertEqual($config->getName(), $name);
-    $this->assertTrue($config, 'Config object created.');
+    $this->assertNotEmpty($config, 'Config object created.');
 
     // Verify the configuration object is empty.
     $this->assertEqual($config->get(), array(), 'New config object is empty.');
@@ -92,12 +92,12 @@ function testReadWriteConfig() {
 
     // Verify the database entry exists.
     $data = $storage->read($name);
-    $this->assertTrue($data);
+    $this->assertNotEmpty($data);
 
     // Read top level value.
     $config = $this->config($name);
     $this->assertEqual($config->getName(), $name);
-    $this->assertTrue($config, 'Config object created.');
+    $this->assertNotEmpty($config, 'Config object created.');
     $this->assertEqual($config->get($key), 'bar', 'Top level configuration value found.');
 
     // Read nested value.
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
index 945e994..d60f282 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigImporterTest.php
@@ -364,7 +364,7 @@ function testSecondaryUpdateDeletedDeleterFirst() {
 
     // The deletee was deleted in
     // \Drupal\config_test\Entity\ConfigTest::postSave().
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertEmpty($entity_storage->load('deletee'));
 
     $other = $entity_storage->load('other');
     $this->assertEqual($other->id(), 'other');
@@ -420,8 +420,8 @@ function testSecondaryUpdateDeletedDeleteeFirst() {
     // Both entities are deleted. ConfigTest::postSave() causes updates of the
     // deleter entity to delete the deletee entity. Since the deleter depends on
     // the deletee, removing the deletee causes the deleter to be removed.
-    $this->assertFalse($entity_storage->load('deleter'));
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertEmpty($entity_storage->load('deleter'));
+    $this->assertEmpty($entity_storage->load('deletee'));
     $logs = $this->configImporter->getErrors();
     $this->assertEqual(count($logs), 0);
   }
@@ -459,8 +459,8 @@ function testSecondaryDeletedDeleteeSecond() {
     $this->configImporter->reset()->import();
 
     $entity_storage = \Drupal::entityManager()->getStorage('config_test');
-    $this->assertFalse($entity_storage->load('deleter'));
-    $this->assertFalse($entity_storage->load('deletee'));
+    $this->assertEmpty($entity_storage->load('deleter'));
+    $this->assertEmpty($entity_storage->load('deletee'));
     // The deletee entity does not exist as the delete worked and although the
     // delete occurred in \Drupal\config_test\Entity\ConfigTest::postDelete()
     // this does not matter.
diff --git a/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php b/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
index 20aa72a..857b2f3 100644
--- a/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Config/ConfigInstallTest.php
@@ -205,7 +205,7 @@ public function testDependencyChecking() {
     $this->installModules(['config_other_module_config_test']);
     $this->installModules(['config_install_dependency_test']);
     $entity = \Drupal::entityManager()->getStorage('config_test')->load('other_module_test_with_dependency');
-    $this->assertTrue($entity, 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
+    $this->assertNotEmpty($entity, 'The config_test.dynamic.other_module_test_with_dependency configuration has been created during install.');
     // Ensure that dependencies can be added during module installation by
     // hooks.
     $this->assertIdentical('config_install_dependency_test', $entity->getDependencies()['module'][0]);
diff --git a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
index f84a9c8..2906a01 100644
--- a/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Database/QueryTest.php
@@ -58,7 +58,7 @@ public function testArrayArgumentsSQLInjection() {
       ->countQuery()
       ->execute()
       ->fetchField();
-    $this->assertFalse($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
+    $this->assertEmpty($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
   }
 
   /**
@@ -89,7 +89,7 @@ public function testConditionOperatorArgumentsSQLInjection() {
       ->countQuery()
       ->execute()
       ->fetchField();
-    $this->assertFalse($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
+    $this->assertEmpty($result, 'SQL injection attempt did not result in a row being inserted in the database table.');
 
     // Attempt SQLi via union query with no unsafe characters.
     $this->enableModules(['user']);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
index 51a204f..a88c53d 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/ContentEntityChangedTest.php
@@ -183,7 +183,7 @@ public function testChanged() {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_de, '=', 'en')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no original entity stored having the changed time of the German translation.'
     );
@@ -199,7 +199,7 @@ public function testChanged() {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_de)->condition('default_langcode', '1')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no entity stored using the default language having the changed time of the German translation.'
     );
@@ -223,7 +223,7 @@ public function testChanged() {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_en, '=', 'de')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'There\'s no German translation stored having the changed time of the original language.'
     );
@@ -255,7 +255,7 @@ public function testChanged() {
     $query = $this->mulChangedStorage->getQuery();
     $ids = $query->condition('changed', $changed_en, '>')->execute();
 
-    $this->assertFalse(
+    $this->assertEmpty(
       $ids,
       'Entity query can access changed time regardless of translation.'
     );
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
index 63ac58d..62ce542 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityFieldTest.php
@@ -606,12 +606,12 @@ public function getContainedStrings(TypedDataInterface $wrapper, $depth, array &
   public function testDataTypes() {
     $types = \Drupal::typedDataManager()->getDefinitions();
     foreach (entity_test_entity_types() as $entity_type) {
-      $this->assertTrue($types['entity:' . $entity_type]['class'], 'Entity data type registered.');
+      $this->assertNotEmpty($types['entity:' . $entity_type]['class'], 'Entity data type registered.');
     }
     // Check bundle types are provided as well.
     entity_test_create_bundle('bundle');
     $types = \Drupal::typedDataManager()->getDefinitions();
-    $this->assertTrue($types['entity:entity_test:bundle']['class'], 'Entity bundle data type registered.');
+    $this->assertNotEmpty($types['entity:entity_test:bundle']['class'], 'Entity bundle data type registered.');
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
index eb0fbf6..a3efd4b 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityQueryTest.php
@@ -481,7 +481,7 @@ public function testCount() {
       ->exists("$field_name.color")
       ->count()
       ->execute();
-     $this->assertFalse($count);
+    $this->assertEquals(0, $count);
   }
 
   /**
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
index 923a13f..d80fa2e 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityTranslationTest.php
@@ -50,7 +50,7 @@ protected function doTestEntityLanguageMethods($entity_type) {
       ));
 
     $this->assertEqual($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)));
+    $this->assertEmpty($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
 
     // Set the value in default language.
     $entity->set($this->fieldName, array(0 => array('value' => 'default value')));
@@ -75,7 +75,7 @@ protected function doTestEntityLanguageMethods($entity_type) {
     $entity->{$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)));
+    $this->assertEmpty($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
 
     // Set the value in default language.
     $entity->set($this->fieldName, array(0 => array('value' => 'default value')));
@@ -332,7 +332,7 @@ protected function doTestEntityTranslationAPI($entity_type) {
 
     $entity->save();
     $hooks = $this->getHooksInfo();
-    $this->assertFalse($hooks, 'No entity translation hooks are fired when creating an entity.');
+    $this->assertEmpty($hooks, 'No entity translation hooks are fired when creating an entity.');
 
     // Verify that we obtain the entity object itself when we attempt to
     // retrieve a translation referring to it.
@@ -504,7 +504,7 @@ protected function doTestEntityTranslationAPI($entity_type) {
     $this->assertTrue(isset($hooks[$entity_type . '_translation_create']), 'The entity-type-specific entity translation creation hook is run when adding and removing a translation without storing it.');
     unset($hooks[$entity_type . '_translation_create']);
 
-    $this->assertFalse($hooks, 'No other hooks beyond the entity translation creation hooks are run when adding and removing a translation without storing it.');
+    $this->assertEmpty($hooks, 'No other hooks beyond the entity translation creation hooks are run when adding and removing a translation without storing it.');
 
     // Check that hooks are fired only when actually storing data.
     $entity = $this->reloadEntity($entity);
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
index 5b0a643..bbd5f9b 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityUUIDTest.php
@@ -55,7 +55,7 @@ protected function assertCRUD($entity_type) {
       ->getStorage($entity_type)
       ->create(array('name' => $this->randomMachineName()));
     $uuid = $entity->uuid();
-    $this->assertTrue($uuid);
+    $this->assertNotEmpty($uuid);
 
     // Verify that the new UUID is different.
     $this->assertNotEqual($custom_entity->uuid(), $uuid);
diff --git a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
index 3e11695..e30c6cc 100644
--- a/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Render/Element/RenderElementTypesTest.php
@@ -190,7 +190,7 @@ function testMoreLink() {
     foreach ($elements as $element) {
       $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
       $result = $xml->xpath($element['expected']);
-      $this->assertTrue($result, '"' . $element['name'] . '" input rendered correctly by drupal_render().');
+      $this->assertNotEmpty($result, '"' . $element['name'] . '" input rendered correctly by drupal_render().');
     }
   }
 
@@ -221,7 +221,7 @@ function testSystemCompactLink() {
     foreach ($elements as $element) {
       $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
       $result = $xml->xpath($element['expected']);
-      $this->assertTrue($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
+      $this->assertNotEmpty($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
     }
 
     // Set admin compact mode on for additional tests.
@@ -237,7 +237,7 @@ function testSystemCompactLink() {
 
     $xml = new \SimpleXMLElement(\Drupal::service('renderer')->renderRoot($element['value']));
     $result = $xml->xpath($element['expected']);
-    $this->assertTrue($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
+    $this->assertNotEmpty($result, '"' . $element['name'] . '" is rendered correctly by drupal_render().');
   }
 
 }
diff --git a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
index b82978c..73e010e 100644
--- a/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Theme/ThemeInstallerTest.php
@@ -40,13 +40,13 @@ protected function setUp() {
    * Verifies that no themes are installed by default.
    */
   function testEmpty() {
-    $this->assertFalse($this->extensionConfig()->get('theme'));
+    $this->assertEmpty($this->extensionConfig()->get('theme'));
 
-    $this->assertFalse(array_keys($this->themeHandler()->listInfo()));
-    $this->assertFalse(array_keys(system_list('theme')));
+    $this->assertEmpty(array_keys($this->themeHandler()->listInfo()));
+    $this->assertEmpty(array_keys(system_list('theme')));
 
     // Rebuilding available themes should always yield results though.
-    $this->assertTrue($this->themeHandler()->rebuildThemeData()['stark'], 'ThemeHandler::rebuildThemeData() yields all available themes.');
+    $this->assertNotEmpty($this->themeHandler()->rebuildThemeData()['stark'], 'ThemeHandler::rebuildThemeData() yields all available themes.');
 
     // theme_get_setting() should return global default theme settings.
     $this->assertIdentical(theme_get_setting('features.favicon'), TRUE);
@@ -85,7 +85,7 @@ function testInstallSubTheme() {
     $base_name = 'test_basetheme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     $this->themeInstaller()->install(array($name));
 
@@ -107,7 +107,7 @@ function testInstallNonExisting() {
     $name = 'non_existing_theme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     try {
       $message = 'ThemeHandler::install() throws InvalidArgumentException upon installing a non-existing theme.';
@@ -119,7 +119,7 @@ function testInstallNonExisting() {
     }
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
   }
 
   /**
@@ -244,7 +244,7 @@ function testUninstallNonExisting() {
     $name = 'non_existing_theme';
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
 
     try {
       $message = 'ThemeHandler::uninstall() throws InvalidArgumentException upon uninstalling a non-existing theme.';
@@ -256,7 +256,7 @@ function testUninstallNonExisting() {
     }
 
     $themes = $this->themeHandler()->listInfo();
-    $this->assertFalse(array_keys($themes));
+    $this->assertEmpty(array_keys($themes));
   }
 
   /**
@@ -266,14 +266,14 @@ function testUninstall() {
     $name = 'test_basetheme';
 
     $this->themeInstaller()->install(array($name));
-    $this->assertTrue($this->config("$name.settings")->get());
+    $this->assertNotEmpty($this->config("$name.settings")->get());
 
     $this->themeInstaller()->uninstall(array($name));
 
-    $this->assertFalse(array_keys($this->themeHandler()->listInfo()));
-    $this->assertFalse(array_keys(system_list('theme')));
+    $this->assertEmpty(array_keys($this->themeHandler()->listInfo()));
+    $this->assertEmpty(array_keys(system_list('theme')));
 
-    $this->assertFalse($this->config("$name.settings")->get());
+    $this->assertEmpty($this->config("$name.settings")->get());
 
     // Ensure that the uninstalled theme can be installed again.
     $this->themeInstaller()->install(array($name));
@@ -281,7 +281,7 @@ function testUninstall() {
     $this->assertTrue(isset($themes[$name]));
     $this->assertEqual($themes[$name]->getName(), $name);
     $this->assertEqual(array_keys(system_list('theme')), array_keys($themes));
-    $this->assertTrue($this->config("$name.settings")->get());
+    $this->assertNotEmpty($this->config("$name.settings")->get());
   }
 
   /**
