.../block/src/Tests/BlockViewBuilderTest.php       | 57 +++-------------------
 .../tests/modules/block_test/block_test.module     |  8 +--
 2 files changed, 7 insertions(+), 58 deletions(-)

diff --git a/core/modules/block/src/Tests/BlockViewBuilderTest.php b/core/modules/block/src/Tests/BlockViewBuilderTest.php
index 7e3c39a..1175480 100644
--- a/core/modules/block/src/Tests/BlockViewBuilderTest.php
+++ b/core/modules/block/src/Tests/BlockViewBuilderTest.php
@@ -190,57 +190,20 @@ protected function verifyRenderCacheHandling() {
   public function testBlockViewBuilderAlter() {
     // Establish baseline.
     $build = $this->getBlockRenderArray();
-    $this->assertIdentical((string) $this->renderer->renderRoot($build), 'Llamas > unicorns!');
+    $this->setRawContent((string)$this->renderer->renderRoot($build));
+    $this->assertIdentical(trim((string)$this->cssSelect('div')[0]), 'Llamas > unicorns!');
 
-    // Enable the block view alter hook that adds a suffix, for basic testing.
+    // Enable the block view alter hook that adds a foo=bar attribute.
     \Drupal::state()->set('block_test_view_alter_suffix', TRUE);
     Cache::invalidateTags($this->block->getCacheTagsToInvalidate());
     $build = $this->getBlockRenderArray();
-    $this->assertTrue(isset($build['#suffix']) && $build['#suffix'] === '<br>Goodbye!', 'A block with content is altered.');
-    $this->assertIdentical((string) $this->renderer->renderRoot($build), 'Llamas &gt; unicorns!<br>Goodbye!');
+    $this->setRawContent((string)$this->renderer->renderRoot($build));
+    $this->assertIdentical(trim((string)$this->cssSelect('[foo=bar]')[0]), 'Llamas > unicorns!');
     \Drupal::state()->set('block_test_view_alter_suffix', FALSE);
 
-    // Force a request via GET so we can test the render cache.
-    $request = \Drupal::request();
-    $request_method = $request->server->get('REQUEST_METHOD');
-    $request->setMethod('GET');
-
     \Drupal::state()->set('block_test.content', NULL);
     Cache::invalidateTags($this->block->getCacheTagsToInvalidate());
 
-    $default_keys = array('entity_view', 'block', 'test_block');
-    $default_tags = array('block_view', 'config:block.block.test_block');
-
-    // Advanced: cached block, but an alter hook adds an additional cache key.
-    $alter_add_key = $this->randomMachineName();
-    \Drupal::state()->set('block_test_view_alter_cache_key', $alter_add_key);
-    $cid = 'entity_view:block:test_block:' . $alter_add_key . ':' . implode(':', \Drupal::service('cache_contexts_manager')->convertTokensToKeys(['languages:' . LanguageInterface::TYPE_INTERFACE, 'theme', 'user.permissions'])->getKeys());
-    $expected_keys = array_merge($default_keys, array($alter_add_key));
-    $build = $this->getBlockRenderArray();
-    $this->assertIdentical($expected_keys, $build['#cache']['keys'], 'An altered cacheable block has the expected cache keys.');
-    $this->assertIdentical((string) $this->renderer->renderRoot($build), '');
-    $cache_entry = $this->container->get('cache.render')->get($cid);
-    $this->assertTrue($cache_entry, 'The block render element has been cached with the expected cache ID.');
-    $expected_tags = array_merge($default_tags, ['rendered']);
-    sort($expected_tags);
-    $this->assertIdentical($cache_entry->tags, $expected_tags, 'The block render element has been cached with the expected cache tags.');
-    $this->container->get('cache.render')->delete($cid);
-
-    // Advanced: cached block, but an alter hook adds an additional cache tag.
-    $alter_add_tag = $this->randomMachineName();
-    \Drupal::state()->set('block_test_view_alter_cache_tag', $alter_add_tag);
-    $expected_tags = Cache::mergeTags($default_tags, array($alter_add_tag));
-    $build = $this->getBlockRenderArray();
-    sort($build['#cache']['tags']);
-    $this->assertIdentical($expected_tags, $build['#cache']['tags'], 'An altered cacheable block has the expected cache tags.');
-    $this->assertIdentical((string) $this->renderer->renderRoot($build), '');
-    $cache_entry = $this->container->get('cache.render')->get($cid);
-    $this->assertTrue($cache_entry, 'The block render element has been cached with the expected cache ID.');
-    $expected_tags = array_merge($default_tags, [$alter_add_tag, 'rendered']);
-    sort($expected_tags);
-    $this->assertIdentical($cache_entry->tags, $expected_tags, 'The block render element has been cached with the expected cache tags.');
-    $this->container->get('cache.render')->delete($cid);
-
     // Advanced: cached block, but an alter hook adds a #pre_render callback to
     // alter the eventual content.
     \Drupal::state()->set('block_test_view_alter_append_pre_render_prefix', TRUE);
@@ -248,9 +211,6 @@ public function testBlockViewBuilderAlter() {
     $this->assertFalse(isset($build['#prefix']), 'The appended #pre_render callback has not yet run before rendering.');
     $this->assertIdentical((string) $this->renderer->renderRoot($build), 'Hiya!<br>');
     $this->assertTrue(isset($build['#prefix']) && $build['#prefix'] === 'Hiya!<br>', 'A cached block without content is altered.');
-
-    // Restore the previous request method.
-    $request->setMethod($request_method);
   }
 
   /**
@@ -260,12 +220,7 @@ public function testBlockViewBuilderAlter() {
    *   The render array.
    */
   protected function getBlockRenderArray() {
-    $build = $this->container->get('entity.manager')->getViewBuilder('block')->view($this->block, 'block');
-
-    // Mock the build array to not require the theme registry.
-    unset($build['#theme']);
-
-    return $build;
+    return $this->container->get('entity.manager')->getViewBuilder('block')->view($this->block, 'block');
   }
 
 }
diff --git a/core/modules/block/tests/modules/block_test/block_test.module b/core/modules/block/tests/modules/block_test/block_test.module
index cec0b24..00f4ce9 100644
--- a/core/modules/block/tests/modules/block_test/block_test.module
+++ b/core/modules/block/tests/modules/block_test/block_test.module
@@ -22,13 +22,7 @@ function block_test_block_alter(&$block_info) {
  */
 function block_test_block_view_test_cache_alter(array &$build, BlockPluginInterface $block) {
   if (\Drupal::state()->get('block_test_view_alter_suffix') !== NULL) {
-    $build['#suffix'] = '<br>Goodbye!';
-  }
-  if (\Drupal::state()->get('block_test_view_alter_cache_key') !== NULL) {
-    $build['#cache']['keys'][] = \Drupal::state()->get('block_test_view_alter_cache_key');
-  }
-  if (\Drupal::state()->get('block_test_view_alter_cache_tag') !== NULL) {
-    $build['#cache']['tags'][] = \Drupal::state()->get('block_test_view_alter_cache_tag');
+    $build['#attributes']['foo'] = 'bar';
   }
   if (\Drupal::state()->get('block_test_view_alter_append_pre_render_prefix') !== NULL) {
     $build['#pre_render'][] = 'block_test_pre_render_alter_content';