.../Tests/Core/Render/RendererBubblingTest.php     | 62 ++++++++++++++++++++--
 .../Drupal/Tests/Core/Render/RendererTestBase.php  |  8 ++-
 2 files changed, 65 insertions(+), 5 deletions(-)

diff --git a/core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php b/core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php
index 56e17fb..405c4ef 100644
--- a/core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererBubblingTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\Tests\Core\Render;
 
+use Drupal\Core\Cache\MemoryBackend;
 use Drupal\Core\KeyValueStore\KeyValueMemoryFactory;
 use Drupal\Core\Render\Element;
 use Drupal\Core\Render\Renderer;
@@ -28,15 +29,15 @@ protected function setUp() {
     $this->rendererConfig['required_cache_contexts'] = [];
 
     parent::setUp();
-
-    $this->setUpRequest();
-    $this->setupMemoryCache();
   }
 
   /**
    * Tests bubbling of assets when NOT using #pre_render callbacks.
    */
   public function testBubblingWithoutPreRender() {
+    $this->setUpRequest();
+    $this->setupMemoryCache();
+
     $this->elementInfo->expects($this->any())
       ->method('getInfo')
       ->willReturn([]);
@@ -77,6 +78,58 @@ public function testBubblingWithoutPreRender() {
   }
 
   /**
+   * Tests cache context bubbling with a custom cache bin.
+   */
+  public function testContextBubblingCustomCacheBin() {
+    $bin = $this->randomMachineName();
+
+    $this->setUpRequest();
+    $this->memoryCache = new MemoryBackend('render');
+    $custom_cache = new MemoryBackend($bin);
+
+    $this->cacheFactory->expects($this->atLeastOnce())
+      ->method('get')
+      ->with($bin)
+      ->willReturnCallback(function($requested_bin) use ($bin, $custom_cache) {
+        if ($requested_bin === $bin) {
+          return $custom_cache;
+        }
+        else {
+          throw new \Exception();
+        }
+      });
+    $this->cacheContextsManager->expects($this->any())
+      ->method('convertTokensToKeys')
+      ->willReturnArgument(0);
+
+    $build = [
+      '#cache' => [
+        'keys' => ['parent'],
+        'contexts' => ['foo'],
+        'bin' => $bin,
+      ],
+      '#markup' => 'parent',
+      'child' => [
+        '#cache' => [
+          'contexts' => ['bar'],
+          'max-age' => 3600,
+        ],
+      ],
+    ];
+    $this->renderer->render($build);
+
+    $this->assertRenderCacheItem('parent:foo', [
+      '#cache_redirect' => TRUE,
+      '#cache' => [
+        'keys' => ['parent'],
+        'contexts' => ['bar', 'foo'],
+        'tags' => [],
+        'bin' => $bin,
+      ],
+    ], $bin);
+  }
+
+  /**
    * Tests cache context bubbling in edge cases, because it affects the CID.
    *
    * ::testBubblingWithPrerender() already tests the common case.
@@ -440,6 +493,9 @@ public function testConditionalCacheContextBubblingSelfHealing() {
    * @dataProvider providerTestBubblingWithPrerender
    */
   public function testBubblingWithPrerender($test_element) {
+    $this->setUpRequest();
+    $this->setupMemoryCache();
+
     // Mock the State service.
     $memory_state = new State(new KeyValueMemoryFactory());;
     \Drupal::getContainer()->set('state', $memory_state);
diff --git a/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php b/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php
index 0a8a28a..19772a3 100644
--- a/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php
+++ b/core/tests/Drupal/Tests/Core/Render/RendererTestBase.php
@@ -172,6 +172,7 @@ protected function setupMemoryCache() {
 
     $this->cacheFactory->expects($this->atLeastOnce())
       ->method('get')
+      ->with('render')
       ->willReturn($this->memoryCache);
   }
 
@@ -195,9 +196,12 @@ protected function setUpRequest($method = 'GET') {
    *   The expected cache ID.
    * @param mixed $data
    *   The expected data for that cache ID.
+   * @param string $bin
+   *   The expected cache bin.
    */
-  protected function assertRenderCacheItem($cid, $data) {
-    $cached = $this->memoryCache->get($cid);
+  protected function assertRenderCacheItem($cid, $data, $bin = 'render') {
+    $cache_backend = $this->cacheFactory->get($bin);
+    $cached = $cache_backend->get($cid);
     $this->assertNotFalse($cached, sprintf('Expected cache item "%s" exists.', $cid));
     if ($cached !== FALSE) {
       $this->assertEquals($data, $cached->data, sprintf('Cache item "%s" has the expected data.', $cid));