PHPUnit_Framework_TestCase::assertFalse PHP Method

    public function assertFalse($a)
    {
        if ($a) {
            throw new Exception('Not false');
        }
    }

 /**
  * @test
  */
 public function notContainsValue()
 {
     $collection = $this->getCollectionInstance(['fuu', 'bar']);
     parent::assertFalse($collection->contains('baz'));
     parent::setExpectedException(KeyIsNotDefinedException::class);
     $collection->get('baz');
 }