public function hasSource()
 {
     $message = new Message('foo');
     $s2 = $this->getMock('JMS\\TranslationBundle\\Model\\SourceInterface');
     $s1 = $this->getMock('JMS\\TranslationBundle\\Model\\SourceInterface');
     $s1->expects($this->once())->method('equals')->with($s2)->will($this->returnValue(true));
     $message->addSource($s1);
     $this->assertTrue($message->hasSource($s2));
 }