/**
  * test engine override
  */
 public function testEngineOverride()
 {
     $Number = new NumberHelperTestObject($this->View, ['engine' => 'TestAppEngine']);
     $this->assertInstanceOf('TestApp\\Utility\\TestAppEngine', $Number->engine());
     Plugin::load('TestPlugin');
     $Number = new NumberHelperTestObject($this->View, ['engine' => 'TestPlugin.TestPluginEngine']);
     $this->assertInstanceOf('TestPlugin\\Utility\\TestPluginEngine', $Number->engine());
     Plugin::unload('TestPlugin');
 }