diff --git a/core/modules/comment/config/schema/comment.source.schema.yml b/core/modules/comment/config/schema/comment.source.schema.yml
new file mode 100644
index 0000000..2d0d51b
--- /dev/null
+++ b/core/modules/comment/config/schema/comment.source.schema.yml
@@ -0,0 +1,35 @@
+migrate.source.d6_comment:
+  type: migrate_source_sql
+  label: 'Drupal 6 comment'
+  mapping:
+    constants:
+      type: mapping
+      label: 'Constants'
+      mapping:
+        entity_type:
+          type: string
+          label: 'Entity type'
+
+migrate.source.d6_comment_variable_per_comment_type:
+  type: migrate_source_sql
+  label: 'Drupal 6 comment variable'
+  mapping:
+    constants:
+      type: migrate_entity_constant
+      label: 'Constants'
+
+migrate.source.d6_comment_entity_form_display_subject:
+  type: migrate_source_sql
+  label: 'Drupal 6 comment subject entity form display'
+  mapping:
+    constants:
+      type: migrate_entity_constant
+      label: 'Constants'
+
+migrate.source.d6_comment_variable:
+  type: migrate_source_sql
+  label: 'Drupal 6 comment variable'
+  mapping:
+    constants:
+      type: migrate_entity_constant
+      label: 'Constants'
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment.yml b/core/modules/comment/migration_templates/d6_comment.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_comment.yml
rename to core/modules/comment/migration_templates/d6_comment.yml
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_display.yml b/core/modules/comment/migration_templates/d6_comment_entity_display.yml
similarity index 99%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_entity_display.yml
rename to core/modules/comment/migration_templates/d6_comment_entity_display.yml
index e06c08f..cb9512b 100644
--- a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_display.yml
+++ b/core/modules/comment/migration_templates/d6_comment_entity_display.yml
@@ -17,7 +17,6 @@ process:
   field_name: 'constants/field_name'
   view_mode: 'constants/view_mode'
   options: 'constants/options'
-
   bundle: node_type
 destination:
   plugin: component_entity_display
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display.yml b/core/modules/comment/migration_templates/d6_comment_entity_form_display.yml
similarity index 99%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display.yml
rename to core/modules/comment/migration_templates/d6_comment_entity_form_display.yml
index a05a11b..e3d7d4c 100644
--- a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display.yml
+++ b/core/modules/comment/migration_templates/d6_comment_entity_form_display.yml
@@ -16,7 +16,6 @@ process:
   field_name: 'constants/field_name'
   form_mode: 'constants/form_mode'
   options: 'constants/options'
-
   bundle: node_type
 destination:
   plugin: component_entity_form_display
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display_subject.yml b/core/modules/comment/migration_templates/d6_comment_entity_form_display_subject.yml
similarity index 99%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display_subject.yml
rename to core/modules/comment/migration_templates/d6_comment_entity_form_display_subject.yml
index a7e3e6b..8c6c607 100644
--- a/core/modules/migrate_drupal/migration_templates/d6_comment_entity_form_display_subject.yml
+++ b/core/modules/comment/migration_templates/d6_comment_entity_form_display_subject.yml
@@ -16,7 +16,6 @@ process:
   field_name: 'constants/field_name'
   form_mode: 'constants/form_mode'
   options: 'constants/options'
-
   hidden:
     plugin: static_map
     source: comment_type
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_field.yml b/core/modules/comment/migration_templates/d6_comment_field.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_field.yml
rename to core/modules/comment/migration_templates/d6_comment_field.yml
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_field_instance.yml b/core/modules/comment/migration_templates/d6_comment_field_instance.yml
similarity index 99%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_field_instance.yml
rename to core/modules/comment/migration_templates/d6_comment_field_instance.yml
index f00b527..c32636e 100644
--- a/core/modules/migrate_drupal/migration_templates/d6_comment_field_instance.yml
+++ b/core/modules/comment/migration_templates/d6_comment_field_instance.yml
@@ -12,7 +12,6 @@ process:
   entity_type: 'constants/entity_type'
   label: 'constants/label'
   required: 'constants/required'
-
   field_name:
     plugin: static_map
     source: comment_subject_field
diff --git a/core/modules/migrate_drupal/migration_templates/d6_comment_type.yml b/core/modules/comment/migration_templates/d6_comment_type.yml
similarity index 100%
rename from core/modules/migrate_drupal/migration_templates/d6_comment_type.yml
rename to core/modules/comment/migration_templates/d6_comment_type.yml
diff --git a/core/modules/migrate/src/Plugin/migrate/destination/EntityComment.php b/core/modules/comment/src/Plugin/migrate/destination/EntityComment.php
similarity index 90%
rename from core/modules/migrate/src/Plugin/migrate/destination/EntityComment.php
rename to core/modules/comment/src/Plugin/migrate/destination/EntityComment.php
index dd460c6..6ecf791 100644
--- a/core/modules/migrate/src/Plugin/migrate/destination/EntityComment.php
+++ b/core/modules/comment/src/Plugin/migrate/destination/EntityComment.php
@@ -2,16 +2,16 @@
 
 /**
  * @file
- * Contains \Drupal\migrate\Plugin\migrate\destination\EntityComment.
+ * Contains \Drupal\comment\Plugin\migrate\destination\EntityComment.
  */
 
-namespace Drupal\migrate\Plugin\migrate\destination;
+namespace Drupal\comment\Plugin\migrate\destination;
 
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Drupal\Core\State\StateInterface;
 use Drupal\migrate\Entity\MigrationInterface;
-use Drupal\migrate\Plugin\MigratePluginManager;
+use Drupal\migrate\Plugin\migrate\destination\EntityContentBase;
 use Drupal\migrate\Row;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
@@ -44,8 +44,6 @@ class EntityComment extends EntityContentBase {
    *   The storage for this entity type.
    * @param array $bundles
    *   The list of bundles this entity type has.
-   * @param \Drupal\migrate\Plugin\MigratePluginManager $plugin_manager
-   *   The migrate plugin manager.
    * @param \Drupal\Core\Entity\EntityManagerInterface $entity_manager
    *   The entity manager service.
    * @param \Drupal\Core\State\StateInterface $state
diff --git a/core/modules/migrate/src/Plugin/migrate/destination/EntityCommentType.php b/core/modules/comment/src/Plugin/migrate/destination/EntityCommentType.php
similarity index 72%
rename from core/modules/migrate/src/Plugin/migrate/destination/EntityCommentType.php
rename to core/modules/comment/src/Plugin/migrate/destination/EntityCommentType.php
index 79be04b..531b6ae 100644
--- a/core/modules/migrate/src/Plugin/migrate/destination/EntityCommentType.php
+++ b/core/modules/comment/src/Plugin/migrate/destination/EntityCommentType.php
@@ -2,11 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\migrate\Plugin\migrate\destination\EntityCommentType.
+ * Contains \Drupal\comment\Plugin\migrate\destination\EntityCommentType.
  */
 
-namespace Drupal\migrate\Plugin\migrate\destination;
+namespace Drupal\comment\Plugin\migrate\destination;
 
+use Drupal\migrate\Plugin\migrate\destination\EntityConfigBase;
 use Drupal\migrate\Row;
 
 /**
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php b/core/modules/comment/src/Plugin/migrate/source/d6/Comment.php
similarity index 96%
rename from core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php
rename to core/modules/comment/src/Plugin/migrate/source/d6/Comment.php
index 56575a9..08a1013 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/Comment.php
+++ b/core/modules/comment/src/Plugin/migrate/source/d6/Comment.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Plugin\migrate\source\d6\Comment.
+ * Contains \Drupal\comment\Plugin\migrate\source\d6\Comment.
  */
 
-namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
+namespace Drupal\comment\Plugin\migrate\source\d6;
 
 use Drupal\migrate\Row;
 use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariable.php b/core/modules/comment/src/Plugin/migrate/source/d6/CommentVariable.php
similarity index 95%
rename from core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariable.php
rename to core/modules/comment/src/Plugin/migrate/source/d6/CommentVariable.php
index e01d28d..2d8f612 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariable.php
+++ b/core/modules/comment/src/Plugin/migrate/source/d6/CommentVariable.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Plugin\migrate\source\d6\CommentVariable.
+ * Contains \Drupal\comment\Plugin\migrate\source\d6\CommentVariable.
  */
 
-namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
+namespace Drupal\comment\Plugin\migrate\source\d6;
 
 use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;
 use Drupal\migrate\Plugin\migrate\source\DummyQueryTrait;
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php b/core/modules/comment/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php
similarity index 92%
rename from core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php
rename to core/modules/comment/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php
index 56313fe..149b1ba 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php
+++ b/core/modules/comment/src/Plugin/migrate/source/d6/CommentVariablePerCommentType.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Plugin\migrate\source\d6\CommentVariablePerCommentType.
+ * Contains \Drupal\comment\Plugin\migrate\source\d6\CommentVariablePerCommentType.
  */
 
-namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
+namespace Drupal\comment\Plugin\migrate\source\d6;
 
 /**
  * @MigrateSource(
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
similarity index 94%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
index a6efb8e..19e74fe 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTest.php
@@ -2,17 +2,18 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
 
 use Drupal\comment\Tests\CommentTestTrait;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade comments.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTypeTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTypeTest.php
similarity index 83%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTypeTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTypeTest.php
index 2b4e07d..fd0b3f1 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentTypeTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentTypeTest.php
@@ -2,17 +2,18 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentTypeTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentTypeTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
 
 use Drupal\comment\Entity\CommentType;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade comment type.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentTypeTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableDisplayBase.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableDisplayBase.php
similarity index 89%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableDisplayBase.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableDisplayBase.php
index e3a0e90..d36dd03 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableDisplayBase.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableDisplayBase.php
@@ -2,10 +2,12 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableDisplayBase.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableDisplayBase.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
+
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Base class for Drupal 6 comment variables to Drupal 8 entity display tests.
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityDisplayTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityDisplayTest.php
similarity index 84%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityDisplayTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityDisplayTest.php
index f63326b..34f4315 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityDisplayTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityDisplayTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableEntityDisplayTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableEntityDisplayTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
 
 /**
  * Upgrade comment variables to entity.display.node.*.default.yml.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentVariableEntityDisplayTest extends MigrateCommentVariableDisplayBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php
similarity index 87%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php
index a65c9fc..6a7f27f 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplaySubjectTest.php
@@ -2,15 +2,17 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableEntityFormDisplaySubjectTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableEntityFormDisplaySubjectTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
+
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade comment subject variable to core.entity_form_display.comment.*.default.yml
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentVariableEntityFormDisplaySubjectTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplayTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplayTest.php
similarity index 81%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplayTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplayTest.php
index 79d8dde..d9820fe 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableEntityFormDisplayTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableEntityFormDisplayTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableEntityFormDisplayTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableEntityFormDisplayTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
 
 /**
  * Upgrade comment variables to core.entity_form_display.node.*.default.yml.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentVariableEntityFormDisplayTest extends MigrateCommentVariableDisplayBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableFieldTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableFieldTest.php
similarity index 86%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableFieldTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableFieldTest.php
index c3986ba..3d55fb5 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableFieldTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableFieldTest.php
@@ -2,17 +2,18 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableFieldTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableFieldTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
 
 use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade comment variables to field.storage.node.comment.yml.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentVariableFieldTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableInstanceTest.php b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableInstanceTest.php
similarity index 92%
rename from core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableInstanceTest.php
rename to core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableInstanceTest.php
index 22747ea..45b0950 100644
--- a/core/modules/migrate_drupal/src/Tests/d6/MigrateCommentVariableInstanceTest.php
+++ b/core/modules/comment/src/Tests/Migrate/d6/MigrateCommentVariableInstanceTest.php
@@ -2,15 +2,17 @@
 
 /**
  * @file
- * Contains \Drupal\migrate_drupal\Tests\d6\MigrateCommentVariableInstanceTest.
+ * Contains \Drupal\comment\Tests\Migrate\d6\MigrateCommentVariableInstanceTest.
  */
 
-namespace Drupal\migrate_drupal\Tests\d6;
+namespace Drupal\comment\Tests\Migrate\d6;
+
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
 
 /**
  * Upgrade comment variables to field.instance.node.*.comment.yml.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class MigrateCommentVariableInstanceTest extends MigrateDrupal6TestBase {
 
diff --git a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentSourceWithHighWaterTest.php b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentSourceWithHighWaterTest.php
similarity index 71%
rename from core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentSourceWithHighWaterTest.php
rename to core/modules/comment/tests/src/Unit/Migrate/d6/CommentSourceWithHighWaterTest.php
index 26a7e51..bc1e7f4 100644
--- a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentSourceWithHighWaterTest.php
+++ b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentSourceWithHighWaterTest.php
@@ -2,15 +2,15 @@
 
 /**
  * @file
- * Contains \Drupal\Tests\migrate_drupal\Unit\source\d6\CommentSourceWithHighWaterTest.
+ * Contains \Drupal\Tests\comment\Unit\Migrate\d6\CommentSourceWithHighWaterTest.
  */
 
-namespace Drupal\Tests\migrate_drupal\Unit\source\d6;
+namespace Drupal\Tests\comment\Unit\Migrate\d6;
 
 /**
  * Tests the Drupal 6 comment source w/ high water handling.
  *
- * @group migrate_drupal
+ * @group comment
  */
 class CommentSourceWithHighWaterTest extends CommentTestBase {
 
diff --git a/core/modules/comment/tests/src/Unit/Migrate/d6/CommentTest.php b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentTest.php
new file mode 100644
index 0000000..f4f5ed3
--- /dev/null
+++ b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentTest.php
@@ -0,0 +1,17 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\comment\Unit\Migrate\d6\CommentTest.
+ */
+
+namespace Drupal\Tests\comment\Unit\Migrate\d6;
+
+/**
+ * Tests D6 comment source plugin.
+ *
+ * @group comment
+ */
+class CommentTest extends CommentTestBase {
+
+}
diff --git a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTestBase.php b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentTestBase.php
similarity index 91%
rename from core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTestBase.php
rename to core/modules/comment/tests/src/Unit/Migrate/d6/CommentTestBase.php
index 0b8f403..ae74a56 100644
--- a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTestBase.php
+++ b/core/modules/comment/tests/src/Unit/Migrate/d6/CommentTestBase.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Tests\migrate_drupal\Unit\source\d6\CommentTestBase.
+ * Contains \Drupal\Tests\comment\Unit\Migrate\d6\CommentTestBase.
  */
 
-namespace Drupal\Tests\migrate_drupal\Unit\source\d6;
+namespace Drupal\Tests\comment\Unit\Migrate\d6;
 
 use Drupal\Tests\migrate\Unit\MigrateSqlSourceTestCase;
 
@@ -16,7 +16,7 @@
 
   // The plugin system is not working during unit testing so the source plugin
   // class needs to be manually specified.
-  const PLUGIN_CLASS = 'Drupal\migrate_drupal\Plugin\migrate\source\d6\Comment';
+  const PLUGIN_CLASS = 'Drupal\comment\Plugin\migrate\source\d6\Comment';
 
   // The fake Migration configuration entity.
   protected $migrationConfiguration = array(
diff --git a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
index fdd6b94..60ac2e1 100644
--- a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
+++ b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
@@ -39,34 +39,6 @@ migrate.source.variable:
           type: string
           label: 'Slash'
 
-migrate.source.d6_comment:
-  type: migrate_source_sql
-  label: 'Drupal 6 comment'
-  mapping:
-    constants:
-      type: mapping
-      label: 'Constants'
-      mapping:
-        entity_type:
-          type: string
-          label: 'Entity type'
-
-migrate.source.d6_comment_variable_per_comment_type:
-  type: migrate_source_sql
-  label: 'Drupal 6 comment variable'
-  mapping:
-    constants:
-      type: migrate_entity_constant
-      label: 'Constants'
-
-migrate.source.d6_comment_entity_form_display_subject:
-  type: migrate_source_sql
-  label: 'Drupal 6 comment subject entity form display'
-  mapping:
-    constants:
-      type: migrate_entity_constant
-      label: 'Constants'
-
 migrate.source.d6_field_instance_per_form_display:
   type: migrate_source_sql
   label: 'Drupal 6 field instance form display'
@@ -94,14 +66,6 @@ migrate.source.variable_multirow:
         type: string
         label: 'Variable'
 
-migrate.source.d6_comment_variable:
-  type: migrate_source_sql
-  label: 'Drupal 6 comment variable'
-  mapping:
-    constants:
-      type: migrate_entity_constant
-      label: 'Constants'
-
 migrate.source.d6_profile_field:
   type: migrate_source_sql
   label: 'Drupal 6 profile field'
diff --git a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTest.php b/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTest.php
deleted file mode 100644
index 660ae4a..0000000
--- a/core/modules/migrate_drupal/tests/src/Unit/source/d6/CommentTest.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Tests\migrate_drupal\Unit\source\d6\CommentTest.
- */
-
-namespace Drupal\Tests\migrate_drupal\Unit\source\d6;
-
-/**
- * Tests D6 comment source plugin.
- *
- * @group migrate_drupal
- */
-class CommentTest extends CommentTestBase {
-
-}
