PHP中的單元測試數據存儲

Question

我正在使用PHPUnit，但是很難使它為用作數據存儲的對象創建良好的模擬和存根。

例：

class urlDisplayer {
    private $storage;
    public function __construct(IUrlStorage $storage) { $this->storage = $storage; }
    public function displayUrl($name) {}
    public function displayLatestUrls($count) {}
}

interface IUrlStorage {
    public function addUrl($name, $url);
    public function getUrl($name);
}

class MysqlUrlStorage implements IUrlStorage {
    // saves and retrieves from database
}

class NonPersistentStorage implements IUrlStorage {
    // just stores for this request
}

例如，如何使PHPUnit存根在使用不同$ names的兩個調用中返回一個以上可能的值？

編輯：示例測試：

public function testUrlDisplayerDisplaysLatestUrls {
    // get mock storage and have it return latest x urls so I can test whether
    // UrlDisplayer really shows the latest x
}

在此測試中，模擬應返回多個url，但是在文檔中，我僅介紹如何返回一個值。

Answer 1

您的問題不是很清楚-但我假設您正在詢問如何在不同情況下使用phpunit的模擬對象返回不同的值？

PHPUnit的模擬類允許您指定一個自定義函數（即：回調函數/方法）-實際上它可以做的事是無限的。

在下面的示例中，我創建了一個模擬的IUrlStorage類，該類將在每次調用時返回其存儲中的下一個URL。

public function setUp()
{
    parent::setUp();
    $this->fixture = new UrlDisplayer(); //change this to however you create your object

    //Create a list of expected URLs for testing across all test cases
    $this->expectedUrls = array(
          'key1' => 'http://www.example.com/url1/'
        , 'key2' => 'http://www.example.net/url2/'
        , 'key3' => 'http://www.example.com/url3/'
    );
}

public function testUrlDisplayerDisplaysLatestUrls {
    //Init        
    $mockStorage = $this->getMock('IUrlStorage');
    $mockStorage->expects($this->any())
        ->method('getUrl')
        ->will( $this->returnCallback(array($this, 'mockgetUrl')) );

    reset($this->expectedUrls); //reset array before testing

    //Actual Tests
    $this->assertGreaterThan(0, count($this->expectedUrls));
    foreach ( $this->expectedUrls as $key => $expected ) {
        $actual = $this->fixture->displayUrl($key);
        $this->assertEquals($expected, $actual);
    }
}

public function mockGetUrl($name)
{
    $value = current($this->expectedUrls);
    next($this->expectedUrls);

    //Return null instead of false when end of array is reached
    return ($value === false) ? null : $value;
}

---

另外，有時更容易簡單地創建一個模擬必要功能的真實類。 定義明確的小型接口尤其容易。

在這種情況下，我建議改用下面的類：

class MockStorage implements IUrlStorage
{
    protected $urls = array();

    public function addUrl($name, $url)
    {
        $this->urls[$name] = $url;
    }

    public function getUrl($name)
    {
        if ( isset($this->urls[$name]) ) {
            return $this->urls[$name];
        }
        return null;
    }
}
?>

然后，在單元測試課程中，您只需實例化夾具即可，如下所示：

public function setUp() {
   $mockStorage = new MockStorage();

   //Add as many expected URLs you want to test for
   $mockStorage->addUrl('name1', 'http://example.com');
   //etc...

   $this->fixture = new UrlDisplayer($mockStorage);
}