diff --git a/core/modules/simpletest/src/TestDiscovery.php b/core/modules/simpletest/src/TestDiscovery.php
index 02bf7071fb..9270b5fe2b 100644
--- a/core/modules/simpletest/src/TestDiscovery.php
+++ b/core/modules/simpletest/src/TestDiscovery.php
@@ -189,14 +189,17 @@ public function getTestClasses($extension = NULL, array $types = []) {
         // abstract class, trait or test fixture.
         continue;
       }
-      // Skip this test class if it requires unavailable modules.
-      // @todo PHPUnit skips tests with unmet requirements when executing a test
-      //   (instead of excluding them upfront). Refactor test runner to follow
-      //   that approach.
+      // Skip this test class if it is a Simpletest-based test and requires
+      // unavailable modules. TestDiscovery should not filter out module
+      // requirements for PHPUnit-based test classes.
+      // @todo Move this behavior to \Drupal\simpletest\TestBase so tests can be
+      //       marked as skipped, instead.
       // @see https://www.drupal.org/node/1273478
-      if (!empty($info['requires']['module'])) {
-        if (array_diff($info['requires']['module'], $this->availableExtensions['module'])) {
-          continue;
+      if (!is_subclass_of($classname, \PHPUnit_Framework_TestCase::class)) {
+        if (!empty($info['requires']['module'])) {
+          if (array_diff($info['requires']['module'], $this->availableExtensions['module'])) {
+            continue;
+          }
         }
       }
 
diff --git a/core/modules/simpletest/tests/src/Functional/MissingDependentModuleUnitTest.php b/core/modules/simpletest/tests/src/Functional/MissingDependentModuleUnitTest.php
deleted file mode 100644
index 885a44c706..0000000000
--- a/core/modules/simpletest/tests/src/Functional/MissingDependentModuleUnitTest.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-
-namespace Drupal\Tests\simpletest\Functional;
-
-use Drupal\Tests\BrowserTestBase;
-
-/**
- * This test should not load since it requires a module that is not found.
- *
- * @group simpletest
- * @dependencies simpletest_missing_module
- */
-class MissingDependentModuleUnitTest extends BrowserTestBase {
-
-  /**
-   * Ensure that this test will not be loaded despite its dependency.
-   */
-  function testFail() {
-    $this->fail('Running test with missing required module.');
-  }
-
-}
diff --git a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
index 66765d9bd5..9880132b2f 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBaseTest.php
@@ -206,6 +206,12 @@ public function testRenderWithTheme() {
   }
 
   /**
+   * Tests that a test case is skipped when it @requires a module not present.
+   *
+   * In order to have a failing test when the annotated test classes run, we
+   * have to run the tests here and discover whether they threw
+   * \PHPUnit_Framework_SkippedTestError.
+   *
    * @covers ::checkRequirements
    * @covers ::checkModuleRequirements
    */
diff --git a/core/tests/fixtures/MissingDependentModuleMethodTest.php b/core/tests/fixtures/MissingDependentModuleMethodTest.php
index 6e59af2846..15f0a23759 100644
--- a/core/tests/fixtures/MissingDependentModuleMethodTest.php
+++ b/core/tests/fixtures/MissingDependentModuleMethodTest.php
@@ -2,11 +2,18 @@
 
 namespace Drupal\KernelTests;
 
-use Drupal\Component\FileCache\FileCacheFactory;
-use Drupal\Core\Database\Database;
-use org\bovigo\vfs\vfsStream;
-use org\bovigo\vfs\visitor\vfsStreamStructureVisitor;
+use Drupal\KernelTests\KernelTestBase;
 
+/**
+ * A fixture test class with @requires annotation.
+ *
+ * This is a fixture class for
+ * \Drupal\KernelTests\KernelTestBaseTest::testRequiresModule().
+ *
+ * This test class should not be discovered by run-tests.sh or phpunit.
+ *
+ * @group fixture
+ */
 class MissingDependentModuleMethodTest extends KernelTestBase {
 
   /**
diff --git a/core/tests/fixtures/MissingDependentModuleTest.php b/core/tests/fixtures/MissingDependentModuleTest.php
index fbd405193b..ce2c49e593 100644
--- a/core/tests/fixtures/MissingDependentModuleTest.php
+++ b/core/tests/fixtures/MissingDependentModuleTest.php
@@ -2,7 +2,29 @@
 
 namespace Drupal\KernelTests;
 
+use Drupal\KernelTests\KernelTestBase;
+
 /**
+ * A fixture test class with @requires annotation.
+ *
+ * This is a fixture class for
+ * \Drupal\KernelTests\KernelTestBaseTest::testRequiresModule().
+ *
+ * This test class should not be discovered by run-tests.sh or phpunit.
+ *
  * @requires module drupal_dne_module
+ * @group fixture
  */
-class MissingDependentModuleTest extends KernelTestBase {}
+class MissingDependentModuleTest extends KernelTestBase {
+
+  /**
+   * Placeholder test method.
+   *
+   * Depending on configuration, PHPUnit might fail a test if it has no test
+   * methods, so we must provide one. This method should never be executed.
+   */
+  public function testRequiresModule() {
+    $this->fail('Running test with missing required module.');
+  }
+
+}