/**
  * @test
  */
 public function existsReturnsTrueIfTheSpecifiedKeyExistsAndIsNull()
 {
     $this->viewHelperVariableContainer->add('NamelessCoder\\Fluid\\ViewHelper\\NonExistent', 'someKey', NULL);
     $this->assertTrue($this->viewHelperVariableContainer->exists('NamelessCoder\\Fluid\\ViewHelper\\NonExistent', 'someKey'));
 }