diff --git a/core/modules/big_pipe/tests/src/FunctionalJavascript/BigPipePlaceholderTest.php b/core/modules/big_pipe/tests/src/FunctionalJavascript/BigPipePlaceholderTest.php
new file mode 100644
index 0000000..1b045e4
--- /dev/null
+++ b/core/modules/big_pipe/tests/src/FunctionalJavascript/BigPipePlaceholderTest.php
@@ -0,0 +1,116 @@
+<?php
+
+namespace Drupal\Tests\big_pipe\FunctionalJavascript;
+
+use Drupal\comment\CommentInterface;
+use Drupal\comment\Entity\Comment;
+use Drupal\comment\Plugin\Field\FieldType\CommentItemInterface;
+use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\editor\Entity\Editor;
+use Drupal\filter\Entity\FilterFormat;
+use Drupal\FunctionalJavascriptTests\JavascriptTestBase;
+use Drupal\simpletest\ContentTypeCreationTrait;
+use Drupal\simpletest\NodeCreationTrait;
+
+/**
+ * Big Pipe placeholder functional tests.
+ *
+ * @group comment
+ */
+class BigPipePlaceholderTest extends JavascriptTestBase {
+
+  use CommentTestTrait;
+  use ContentTypeCreationTrait;
+  use NodeCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = [
+    'node',
+    'comment',
+    'big_pipe',
+    'history',
+    'editor',
+    'ckeditor',
+    'filter',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setUp() {
+    parent::setUp();
+
+    // Use the comment test theme.
+    $this->container->get('theme_installer')->install(['big_pipe_test_theme']);
+    $this->container->get('config.factory')->getEditable('system.theme')->set('default', 'big_pipe_test_theme')->save();
+    // Clear the theme registry.
+    $this->container->set('theme.registry', NULL);
+
+    // Ensure an `article` node type exists.
+    $this->createContentType(['type' => 'article']);
+    $this->addDefaultCommentField('node', 'article');
+
+    // Enable CKEditor.
+    FilterFormat::create([
+      'format' => 'full_html',
+      'name' => 'Full HTML',
+      'weight' => 1,
+      'filters' => [],
+    ])->save();
+    $settings['toolbar']['rows'] = [
+      [
+        [
+          'name' => 'Links',
+          'items' => [
+            'DrupalLink',
+            'DrupalUnlink',
+          ],
+        ],
+      ],
+    ];
+    $editor = Editor::create([
+      'format' => 'full_html',
+      'editor' => 'ckeditor',
+    ]);
+    $editor->setSettings($settings);
+    $editor->save();
+
+    $admin_user = $this->drupalCreateUser([
+      'access comments',
+      'post comments',
+      'use text format full_html',
+    ]);
+    $this->drupalLogin($admin_user);
+  }
+
+  /**
+   * Ensure comment form works with history and big_pipe modules.
+   */
+  public function testCommentForm() {
+    $node = $this->createNode([
+      'type' => 'article',
+      'comment' => CommentItemInterface::OPEN,
+    ]);
+    // Create some comments.
+    foreach (range(1, 5) as $i) {
+      $comment = Comment::create([
+        'status' => CommentInterface::PUBLISHED,
+        'field_name' => 'comment',
+        'entity_type' => 'node',
+        'entity_id' => $node->id(),
+      ]);
+      $comment->save();
+    }
+    $this->drupalGet($node->toUrl()->toString());
+    // Confirm that CKEditor loaded.
+    $javascript = <<<JS
+    (function(){
+      return Object.keys(CKEDITOR.instances).length > 0;
+    }());
+JS;
+    $this->assertJsCondition($javascript);
+  }
+
+}
diff --git a/core/modules/big_pipe/tests/themes/big_pipe_test_theme/big_pipe_test_theme.info.yml b/core/modules/big_pipe/tests/themes/big_pipe_test_theme/big_pipe_test_theme.info.yml
new file mode 100644
index 0000000..d2296e6
--- /dev/null
+++ b/core/modules/big_pipe/tests/themes/big_pipe_test_theme/big_pipe_test_theme.info.yml
@@ -0,0 +1,5 @@
+name: 'Big Pipe test theme'
+type: theme
+description: 'Theme for testing the duplicate big pipe placeholders'
+version: VERSION
+core: 8.x
diff --git a/core/modules/big_pipe/tests/themes/big_pipe_test_theme/templates/field--comment.html.twig b/core/modules/big_pipe/tests/themes/big_pipe_test_theme/templates/field--comment.html.twig
new file mode 100644
index 0000000..b59fc87
--- /dev/null
+++ b/core/modules/big_pipe/tests/themes/big_pipe_test_theme/templates/field--comment.html.twig
@@ -0,0 +1,21 @@
+{#
+/**
+ * @file
+ * Test that comments still work with the form above instead of below.
+ */
+#}
+<section{{ attributes }}>
+  {% if comments and not label_hidden %}
+    {{ title_prefix }}
+    <h2{{ title_attributes }}>{{ label }}</h2>
+    {{ title_suffix }}
+  {% endif %}
+
+  {% if comment_form %}
+    <h2{{ content_attributes }}>{{ 'Add new comment'|t }}</h2>
+    {{ comment_form }}
+  {% endif %}
+
+  {{ comments }}
+
+</section>