[DDC-2700] Add test and fix CS.

lib/Doctrine/ORM/Mapping/ClassMetadataInfo.php

@@ -1031,12 +1031,14 @@ class ClassMetadataInfo implements ClassMetadata
      */
     public function isIdentifier($fieldName)
     {
-        if (0 == count($this->identifier)) {
+        if ( ! $this->identifier) {
             return false;
         }
+
         if ( ! $this->isIdentifierComposite) {
             return $fieldName === $this->identifier[0];
         }
+
         return in_array($fieldName, $this->identifier);
     }
 

tests/Doctrine/Tests/ORM/Mapping/ClassMetadataTest.php

@@ -1091,6 +1091,25 @@ class ClassMetadataTest extends \Doctrine\Tests\OrmTestCase
 
         $this->assertEquals(array('sequenceName' => 'foo', 'quoted' => true), $cm->sequenceGeneratorDefinition);
     }
+
+    /**
+     * @group DDC-2700
+     */
+    public function testIsIdentifierMappedSuperClass()
+    {
+        $class = new ClassMetadata(__NAMESPACE__ . '\\DDC2700MappedSuperClass');
+
+        $this->assertFalse($class->isIdentifier('foo'));
+    }
+}
+
+/**
+ * @MappedSuperclass
+ */
+class DDC2700MappedSuperClass
+{
+    /** @Column */
+    private $foo;
 }
 
 class MyNamespacedNamingStrategy extends \Doctrine\ORM\Mapping\DefaultNamingStrategy