diff --git a/core/tests/Drupal/Tests/Core/Serialization/YamlTest.php b/core/tests/Drupal/Tests/Core/Serialization/YamlTest.php
index 5b62289..2b155cb 100644
--- a/core/tests/Drupal/Tests/Core/Serialization/YamlTest.php
+++ b/core/tests/Drupal/Tests/Core/Serialization/YamlTest.php
@@ -128,4 +128,33 @@ public function providerYamlNodeAnchors() {
     return $data;
   }
 
+  /**
+   * Tests all YAML files are decoded in the same way with both Symfony and PECL.
+   *
+   * @dataProvider providerYamlFilesInCore
+   */
+  public function testYamlFilesInCore($file) {
+    $data = file_get_contents($file);
+    $symfony = new YamlSymfony();
+    $pecl = new YamlPecl();
+    $this->assertEquals($symfony->decode($data), $pecl->decode($data));
+  }
+
+  /**
+   * Data provider for YAML files in core test.
+   * @return array
+   */
+  public function providerYamlFilesInCore() {
+    $files = array();
+    $dirs = new \RecursiveIteratorIterator(new \RecursiveDirectoryIterator(__DIR__ . '/../../../../../', \RecursiveDirectoryIterator::FOLLOW_SYMLINKS));
+    foreach ($dirs as $dir) {
+      $pathname = $dir->getPathname();
+      // Exclude vendor.
+      if ($dir->getExtension() == 'yml' && strpos($pathname, '/../../../../../vendor') === FALSE) {
+        $files[] = array($dir->getRealPath());
+      }
+    }
+    return $files;
+  }
+
 }