diff --git a/core/lib/Drupal/Component/Discovery/YamlDiscovery.php b/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
index bf4ee15aa778b17a6bfe011b2dab9945f04e0980..1d147fd08ba1ff29acc98a36e35507f24e874b04 100644
--- a/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
+++ b/core/lib/Drupal/Component/Discovery/YamlDiscovery.php
@@ -48,7 +48,9 @@ public function __construct($name, array $directories) {
   public function findAll() {
     $all = array();
     foreach ($this->findFiles() as $provider => $file) {
-      $all[$provider] = Yaml::decode(file_get_contents($file));
+      // If a file is empty or its contents are commented out, return an empty
+      // array instead of NULL for type consistency.
+      $all[$provider] = Yaml::decode(file_get_contents($file)) ?: [];
     }
 
     return $all;
diff --git a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_1/test_1.test.yml b/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_1/test_1.test.yml
deleted file mode 100644
index b3275362517072a94da46b9f7966cdbc97ddc670..0000000000000000000000000000000000000000
--- a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_1/test_1.test.yml
+++ /dev/null
@@ -1 +0,0 @@
-name: test
diff --git a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_2.test.yml b/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_2.test.yml
deleted file mode 100644
index b3275362517072a94da46b9f7966cdbc97ddc670..0000000000000000000000000000000000000000
--- a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_2.test.yml
+++ /dev/null
@@ -1 +0,0 @@
-name: test
diff --git a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_3.test.yml b/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_3.test.yml
deleted file mode 100644
index b3275362517072a94da46b9f7966cdbc97ddc670..0000000000000000000000000000000000000000
--- a/core/tests/Drupal/Tests/Component/Discovery/Fixtures/test_2/test_3.test.yml
+++ /dev/null
@@ -1 +0,0 @@
-name: test
diff --git a/core/tests/Drupal/Tests/Component/Discovery/YamlDiscoveryTest.php b/core/tests/Drupal/Tests/Component/Discovery/YamlDiscoveryTest.php
index a5469922a98fe9ba0295c246d255ba933c1f52b8..1849cd53a2ef86c4524526bf996e7dd32d765121 100644
--- a/core/tests/Drupal/Tests/Component/Discovery/YamlDiscoveryTest.php
+++ b/core/tests/Drupal/Tests/Component/Discovery/YamlDiscoveryTest.php
@@ -9,6 +9,9 @@
 
 use Drupal\Tests\UnitTestCase;
 use Drupal\Component\Discovery\YamlDiscovery;
+use org\bovigo\vfs\vfsStream;
+use org\bovigo\vfs\vfsStreamWrapper;
+use org\bovigo\vfs\vfsStreamDirectory;
 
 /**
  * YamlDiscovery component unit tests.
@@ -21,13 +24,26 @@ class YamlDiscoveryTest extends UnitTestCase {
    * Tests the YAML file discovery.
    */
   public function testDiscovery() {
-    $base_path = __DIR__ . '/Fixtures';
+    vfsStreamWrapper::register();
+    $root = new vfsStreamDirectory('modules');
+    vfsStreamWrapper::setRoot($root);
+    $url = vfsStream::url('modules');
+
+    mkdir($url . '/test_1');
+    file_put_contents($url . '/test_1/test_1.test.yml', 'name: test');
+    file_put_contents($url . '/test_1/test_2.test.yml', 'name: test');
+
+    mkdir($url . '/test_2');
+    file_put_contents($url . '/test_2/test_3.test.yml', 'name: test');
+    // Write an empty YAML file.
+    file_put_contents($url . '/test_2/test_4.test.yml', '');
+
     // Set up the directories to search.
     $directories = array(
-      'test_1' => $base_path . '/test_1',
-      'test_2' => $base_path . '/test_2',
-      // Use the same directory with a different provider name.
-      'test_3' => $base_path . '/test_2',
+      'test_1' => $url . '/test_1',
+      'test_2' => $url . '/test_1',
+      'test_3' => $url . '/test_2',
+      'test_4' => $url . '/test_2',
     );
 
     $discovery = new YamlDiscovery('test', $directories);
@@ -37,11 +53,14 @@ public function testDiscovery() {
     $this->assertArrayHasKey('test_1', $data);
     $this->assertArrayHasKey('test_2', $data);
     $this->assertArrayHasKey('test_3', $data);
+    $this->assertArrayHasKey('test_4', $data);
 
-    foreach ($data as $item) {
-      $this->assertArrayHasKey('name', $item);
-      $this->assertEquals($item['name'], 'test');
+    foreach (array('test_1', 'test_2', 'test_3') as $key) {
+      $this->assertArrayHasKey('name', $data[$key]);
+      $this->assertEquals($data[$key]['name'], 'test');
     }
+
+    $this->assertSame(array(), $data['test_4']);
   }
 
 }