public function testRemoveEmpty() { $fileReader = new DummyFileReader(); $jsonFileReader = new Json($fileReader); $fileManager = new FileManager($jsonFileReader); $result = $fileManager->remove(0); //$this->assertSame(4, $result); can be 2. https://travis-ci.org/Raphhh/balloon/jobs/60049978 $result = $fileManager->getAll(); $this->assertSame([], $result); }