bug symfony#20828 [Validator] Fix init of YamlFileLoader::$classes for empty files (nicolas-grekas)

This PR was merged into the 2.7 branch.

Discussion
----------

[Validator] Fix init of YamlFileLoader::$classes for empty files

| Q             | A
| ------------- | ---
| Branch?       | 2.7
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | symfony#20761
| License       | MIT
| Doc PR        | -

Commits
-------

073a1da [Validator] Fix init of YamlFileLoader::$classes for empty files

Author: nicolas-grekas

src/Symfony/Component/Validator/Mapping/Loader/YamlFileLoader.php

@@ -46,13 +46,7 @@ public function loadClassMetadata(ClassMetadata $metadata)
                 $this->yamlParser = new YamlParser();
             }
 
-            // This method may throw an exception. Do not modify the class'
-            // state before it completes
-            if (false === ($classes = $this->parseFile($this->file))) {
-                return false;
-            }
-
-            $this->classes = $classes;
+            $this->classes = $this->parseFile($this->file);
 
             if (isset($this->classes['namespaces'])) {
                 foreach ($this->classes['namespaces'] as $alias => $namespace) {
@@ -111,7 +105,7 @@ protected function parseNodes(array $nodes)
      *
      * @param string $path The path of the YAML file
      *
-     * @return array|null The class descriptions or null, if the file was empty
+     * @return array The class descriptions
      *
      * @throws \InvalidArgumentException If the file could not be loaded or did
      *                                   not contain a YAML array
@@ -126,7 +120,7 @@ private function parseFile($path)
 
         // empty file
         if (null === $classes) {
-            return;
+            return array();
         }
 
         // not an array

src/Symfony/Component/Validator/Tests/Mapping/Loader/YamlFileLoaderTest.php

@@ -31,6 +31,10 @@ public function testLoadClassMetadataReturnsFalseIfEmpty()
         $metadata = new ClassMetadata('Symfony\Component\Validator\Tests\Fixtures\Entity');
 
         $this->assertFalse($loader->loadClassMetadata($metadata));
+
+        $r = new \ReflectionProperty($loader, 'classes');
+        $r->setAccessible(true);
+        $this->assertSame(array(), $r->getValue($loader));
     }
 
     /**