public function testThrowExceptionWhenKeyIsMissing()
{
// Expect an Exception
$this->setExpectedException('PhilippBaschke\\ACFProInstaller\\Exceptions\\MissingKeyException', 'ACF_PRO_KEY');
// Mock a RemoteFilesystem
$rfs = $this->getMockBuilder('Composer\\Util\\RemoteFilesystem')->disableOriginalConstructor()->getMock();
// Mock an Event
$event = $this->getMockBuilder('Composer\\Plugin\\PreFileDownloadEvent')->disableOriginalConstructor()->setMethods(['getProcessedUrl', 'getRemoteFilesystem'])->getMock();
$event->expects($this->once())->method('getProcessedUrl')->willReturn(self::REPO_URL);
$event->expects($this->once())->method('getRemoteFilesystem')->willReturn($rfs);
// Call addKey
$plugin = new Plugin();
$plugin->addKey($event);
}