Effective Unit Testing

KKBOX 內訓簡報

Transcript

1. 有效的單元測試
   Jace Ju @ KKBOX
   https://commons.wikimedia.org/
   

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2. 一直以來，我們寫的測試就像…
   

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4. 捫心自問，你寫的測試有用嗎？
   

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5. 如果你常有這些抱怨…
   測試容易因為執行環境問題而失敗
   同事說看不懂你在測試什麼
   新增或修改測試要做的事很多
   常常沒有測試到真正重要的部份
   

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6. 你就需要瞭解測試的…
   測試替身 可讀性 可維護性 可靠性
   

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7. 測試替身
   Test Doubles
   https://www.pinterest.com
   

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8. 待測程式碼
   真實物件
   測試替身 測試替身
   測試替身
   

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9. 替身的作用
   隔離待測
   程式
   加速測試
   執行
   讓測試結
   果穩定
   模擬特殊
   狀況
   曝露隱藏
   的行為
   

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10. 替身的類型
    Stub
    Fake
    Spy
    Mock
    

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12. Stub
    繼承或實作相依類別與介面
    寫死的回傳值 (包含 Exception)
    Extract And Override
    

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13. class StubRepository implements RepositoryInterface
    {
    public function findUser(int $id): User
    {
    return new StubUser([ 'id' => 1 ]);
    }
    public function fetchUsers(array $ids): Collection
    {
    throw new \InvalidArgumentException();
    }
    }
    Stub 範例
    

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14. Fake
    提供輕量級實作
    執行速度很快
    建立成本較低
    

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15. class FakeSession implements SessionInterface
    {
    private $storage = [];
    public function put($name, $value)
    {
    $this->storage[$name] = $value;
    }
    public function get($name)
    {
    return $this->storage[$name] ?? null;
    }
    }
    Fake 範例
    

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16. 
    
    
    
    
    
    
    
    
    
    
    Laravel 中的應用
    

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17. Spy
    在相依物件上加入 spy 程式
    記錄相依物件的方法有無被呼叫
    事後透過 spy 物件的方法驗證
    

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18. $logger = Mockery::spy(Logger::class);
    $auth = new Auth($logger);
    $auth->login('user', 'pass');
    $logger->shouldHaveReceived('log')
    ->once();
    Spy 範例
    

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19. Mock
    進階版的 Stub 和 Spy
    讓不同輸入參數對應不同輸出
    精準控制方法的被呼叫次數
    

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20. $service = Mockery::mock(UserService::class);
    $service->shouldReceive('authenticate')
    ->with('jaceju', '123456')
    ->andReturn(false);
    $service->shouldReceive('authenticate')
    ->with('butany', '123456')
    ->andReturn(true);
    $userController = new UserController($service);
    $actual = $userController->login('jaceju', '123456');
    $this->assertFalse($actual);
    $actual = $userController->login('butany', '123456');
    $this->assertTrue($actual);
    Mock 範例
    

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21. Spy -
    事後驗證行為 Mock - 事前定義
    對應輸出
    

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22. 替身反模式
    • 所有相依類別都用替身隔離
    假測試
    • 重構時也必須去修改測試中的替身
    過度的實作耦合
    • 資料庫邏輯被徹底隔離
    設計過當
    https://speakerdeck.com/adamwathan/tdd-the-good-parts-1
    

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23. 替身反模式解法
    • 可控制的部份就別用替身
    使用真實協作物件
    • 從抽象層次去驗證需求
    別驗證細節
    • 測試時改用 sqlite::memory:
    使用 ORM
    

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24. 替身就是造假的藝術
    https://zh.wikipedia.org/
    

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25. 可讀性
    Readability
    http://uxmastery.com/
    

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26. 可讀性原則
    別讓閱讀者思考
    一個測試只測試一個情境
    

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27. 可讀性反模式
    斷言不直覺
    斷言範圍太廣
    一次測太多事
    過份保護
    

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28. 斷言不直覺
    $this->assertTrue(array_key_exists('foo', $ary));
    $this->assertEquals(3, strpos('foobar', 'bar'));
    

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29. 用更直覺的斷言
    $this->assertArrayHasKey('foo', $ary);
    $this->assertContains('bar', 'foobar');
    

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30. /** @expectedException \Exception */
    public function textServiceShouldThrowExceptionWhenSomethingWrong()
    {
    // ...
    $service = new UserService();
    $service->getVerifiedUsers();
    }
    斷言範圍太廣
    

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31. /**
    * @expectedException \Illuminate\Database\QueryException
    */
    public function textThrowExceptionWhenQueryFailed()
    {
    // ...
    $service = new UserService();
    $service->getVerifiedUsers();
    }
    /**
    * @expectedException \Predis\Connection\ConnectionException
    */
    public function textThrowExceptionWhenRedisIsDisconnect()
    {
    // ...
    $service = new UserService();
    $service->getVerifiedUsers();
    }
    縮小斷言範圍
    

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32. public function testAlbum()
    {
    $albumId = 10001;
    $albumIds = [$albumId];
    $wrapper = new ImageApiWrapper();
    $actual = $wrapper->getAlbumUrls($albumIds);
    $this->assertEquals('10001/300x300.jpg', $actual[$albumId]);
    $actual = $wrapper->getAlbumInfos($albumIds);
    $this->assertEquals('10001/300x300.jpg', $actual[$albumId]['url']);
    }
    一次測太多事
    

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33. protected function setUp()
    {
    $this->wrapper = new ImageApiWrapper();
    }
    public function testGetAlbumUrlsSuccess()
    {
    $albumId = 10001;
    $expected = [
    $albumId => '10001/300x300.jpg',
    ];
    $actual = $this->wrapper->getAlbumUrls([$albumId]);
    $this->assertEquals($expected, $actual);
    }
    一次只測一件事
    

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34. public function testGetAlbumInfoSuccess()
    {
    $albumId = 10001;
    $expected = [
    $albumId => [
    'id' => '10001',
    'url' => '10001/300x300.jpg',
    ],
    ];
    $actual = $this->wrapper->getAlbumInfos([$albumId], 'tw');
    $this->assertEquals($expected, $actual);
    }
    一次只測一件事 (續)
    

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35. $users = (new UserRepository())->fetchVerifiedUsers();
    $this->assertNotNull($users);
    $this->assertCount(5, $users);
    過度保護
    

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36. $users = (new UserRepository())->fetchVerifiedUsers();
    $this->assertNotNull($users);
    $this->assertCount(5, $users);
    刪除不必要的斷言
    

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37. 可維護性
    Maintainability
    http://soniasaelensdeco.canalblog.com/
    

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38. 可維護性原則
    不論誰接手都能運作
    減少不穩定的狀況
    

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39. 可維護性反模式
    條件邏輯
    重複的程式碼
    相依的測試
    脆弱的測試
    

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40. $service = new UserService();
    $verifiedUsers = $service->getVerifiedUsers();
    foreach ($verifiedUsers as $index => $verifiedUser) {
    if ($index === 0) {
    $this->assertEquals('butany', $verifiedUser['name']);
    }
    if ($index === 1) {
    $this->assertEquals('jaceju', $verifiedUser['name']);
    }
    }
    條件邏輯
    

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41. public function testUserServiceShouldReturnExpectedVerifiedUsers()
    {
    $service = new UserService();
    $verifiedUsers = $service->getVerifiedUsers();
    $this->assertCount(2, $verifiedUsers);
    $this->assertArrayHasKey('name', $verifiedUsers[0]);
    $this->assertEquals('butany', $verifiedUsers[0]['name']);
    $this->assertArrayHasKey('name', $verifiedUsers[1]);
    $this->assertEquals('jaceju', $verifiedUsers[1]['name']);
    }
    重複的程式碼
    

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42. class UserServiceTest
    {
    use AssertionHelper;
    private $service;
    public function setUp()
    {
    $this->service = new UserService();
    }
    }
    trait AssertionHelper
    {
    private function assertArrayHasKeyWithValue($array, $key, $value)
    {
    $this->assertArrayHasKey($key, $array);
    $this->assertEquals($value, $array[$key]);
    }
    }
    利用 setUp 和 Trait
    

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43. public function testUserServiceShouldReturnExpectedVerifiedUsers()
    {
    $verifiedUsers = $this->service->getVerifiedUsers();
    $this->assertCount(2, $verifiedUsers);
    $this->assertArrayHasKeyWithValue($verifiedUsers[0], 'name', 'butany');
    $this->assertArrayHasKeyWithValue($verifiedUsers[1], 'name', 'jaceju');
    }
    利用 setUp 和 Trait (續)
    

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44. class ConfigTest extends TestCase
    {
    private $config;
    public function testAddConfigSuccess()
    {
    $configFile = __DIR__ . '/fixture/config.json';
    $this->config = new Config($configFile);
    $this->config->add('debug', true);
    $this->assertObjectHasAttribute('debug', $this->config);
    }
    public function testInjectConfigToAppShouldWork()
    {
    $app = new App($this->config);
    assertThat($app->debugMode, isTrue());
    }
    }
    相依的測試
    

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45. class AppTest extends TestCase
    {
    public function testInjectConfigToAppShouldWork()
    {
    $config = Mockery::mock(Config::class);
    $config->shouldRecive('toArray')
    ->andReturn(['debug' => true]);
    $app = new App($config);
    assertThat($app->debugMode, isTrue());
    }
    }
    獨立每個測試案例
    

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46. 脆弱的測試
    不可控的執行環境
    寫死的檔案路徑
    緩慢的等待 (Sleep)
    

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47. 可靠性
    Reliability
    

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48. 可靠性原則
    去除任何的疑惑
    要真正是可信賴的
    

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49. 可靠性反模式
    被註解的測試
    永不失敗的測試
    虛假的測試
    有條件的測試
    

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50. class AppTest extends TestCase
    {
    public function testInjectConfigToAppShouldWork()
    {
    // $config = Mockery::mock(Config::class);
    // $config->shouldRecive('toArray')
    // ->andReturn(['debug' => true]);
    // $app = new App($config);
    // assertThat($app->debugMode, isTrue());
    }
    }
    被註解的測試
    

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51. class ImageApiWrapperTest extends TestCase
    {
    public function testDevelopmentMode()
    {
    $dev = true;
    $app = new ImageApiWrapper($dev);
    }
    }
    永不失敗的測試
    

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52. /** @test */
    public function it_should_get_empty_array_when_get_urls_with_invalid_id()
    {
    $albumId = 'invalid_id';
    $albumIds = [$albumId];
    $wrapper = new ImageApiWrapper();
    $actual = $wrapper->getAlbumUrls($albumIds);
    $expected = [
    $albumId => 'noimg/300x300.jpg',
    ];
    $this->assertEquals($expected, $actual);
    }
    虛假的測試
    

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53. public function testRunListCommandAtHomeDirectory()
    {
    $expectedFile = 'hello.txt';
    $targetDirectory = '/home/jaceju';
    $this->createFile($expectedFile, $targetDirectory);
    $command = new ListCommand($targetDirectory);
    $process = Process::run($command);
    if ($process->getExitCode() === 0) {
    $this->assertEquals($expectedFile, $process->getOutput());
    }
    }
    有條件的測試
    

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54. public function testRunListCommandAtHomeDirectoryShouldGetExpectedFile()
    {
    $expectedFile = 'hello.txt';
    $targetDirectory = '/home/jaceju';
    $this->createFile($expectedFile, $targetDirectory);
    $command = new ListCommand($targetDirectory);
    $process = Process::run($command);
    $this->assertEquals(0, $process->getExitCode());
    $this->assertEquals($expectedFile, $process->getOutput());
    }
    用斷言取代條件式
    

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55. 總結
    Summary
    https://www.bankinghub.eu/
    

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56. 驗證需求而不是驗證細節。
    一次只測試一件事。
    要有清楚的斷言。
    只隔離不可控的因素。
    

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58. http://newsletters.getresponse.com/
    

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