.../EntityResourceRestTestCoverageTest.php         | 57 ++++++++++++++++------
 1 file changed, 41 insertions(+), 16 deletions(-)

diff --git a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php
index f82f9a4..9e5ed54 100644
--- a/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php
+++ b/core/modules/rest/tests/src/Functional/EntityResource/EntityResourceRestTestCoverageTest.php
@@ -59,16 +59,28 @@ protected function setUp() {
    * Tests that all core content/config entity types have REST test coverage.
    */
   public function testEntityTypeRestTestCoverage() {
-    $tests = [
-      '\Drupal\Tests\rest\Functional\EntityResource' => [
-        'JsonAnonTest',
-        'JsonBasicAuthTest',
-        'JsonCookieTest',
+    $default_test_locations = [
+      // Test coverage for formats provided by the 'serialization' module.
+      'serialization' => [
+        'possible paths' => [
+          '\Drupal\Tests\rest\Functional\EntityResource\CLASS\CLASS',
+        ],
+        'class suffix' => [
+          'JsonAnonTest',
+          'JsonBasicAuthTest',
+          'JsonCookieTest',
+        ],
       ],
-      '\Drupal\Tests\hal\Functional\EntityResource' => [
-        'HalJsonAnonTest',
-        'HalJsonBasicAuthTest',
-        'HalJsonCookieTest',
+      // Test coverage for formats provided by the 'hal' module.
+      'hal' => [
+        'possible paths' => [
+          '\Drupal\Tests\hal\Functional\EntityResource\CLASS\CLASS',
+        ],
+        'class suffix' => [
+          'HalJsonAnonTest',
+          'HalJsonBasicAuthTest',
+          'HalJsonCookieTest',
+        ],
       ],
     ];
 
@@ -77,13 +89,26 @@ public function testEntityTypeRestTestCoverage() {
       $class_name_full = $info->getClass();
       $parts = explode('\\', $class_name_full);
       $class_name = end($parts);
-      foreach ($tests as $path => $postfixes) {
-        foreach ($postfixes as $postfix) {
-          $class = $path . '\\' . $class_name . '\\' . $class_name . $postfix;
-          if (!class_exists($class)) {
-            $problems[] = "$class_name ($class_name_full)";
-            break 2;
-          }
+      $module_name = $parts[1];
+
+      // The test class can live either in the REST/HAL module, or in the module
+      // providing the entity type.
+      $tests = $default_test_locations;
+      $tests['serialization']['possible paths'][] = '\Drupal\Tests\\' . $module_name . '\Functional\Rest\CLASS';
+      $tests['hal']['possible paths'][] = '\Drupal\Tests\\' . $module_name . '\Functional\Hal\CLASS';
+
+      foreach ($tests as $module => $info) {
+        $possible_paths = $info['possible paths'];
+        foreach ($info['class suffix'] as $postfix) {
+          do {
+            $path = array_shift($possible_paths);
+            $class = str_replace('CLASS', $class_name, $path . $postfix);
+            if (class_exists($class)) {
+              continue 3;
+            }
+          } while (!empty($possible_paths));
+          $problems[] = "$class_name ($class_name_full)";
+          break 2;
         }
       }
     }