如何使用 mockito 为控制器类编写单元测试用例

在测试中，您似乎已经交叉了几件事。有集成测试和单元测试。集成测试将测试所有（或几乎所有）都挂接在一起 - 所以你使用Spring配置文件非常接近真实的配置文件，并且对象的真实示例被注入到你的测试类中。这主要是我使用的，但我将其与@RunWith（SpringJUnit4ClassRunner.class）结合使用。@ContextConfiguration

如果您使用的是Mockito（或任何模拟框架），这通常是因为您希望将要测试的类与其他类的实际实现隔离开来。因此，例如，您不必设计一种方法来让您的RegisterService抛出一个NumberFormatException来测试该代码路径，而只需告诉模拟的RegingService来执行此操作即可。还有很多其他的例子，使用模拟比使用真正的类实例更方便。

就这样，那堂小课结束了。以下是我如何重写你的测试类（带有一个额外的示例并在此过程中进行注释）。

@RunWith(MockitoJUnitRunner.class)
public class RegistrationControllerTest {

    // Create an instance of what you are going to test.
    // When using the @InjectMocks annotation, you must create the instance in
    // the constructor or in the field declaration.
    @InjectMocks
    private RegistrationController controllerUT = new RegistrationController();

    // The @Mock annotation creates the mock instance of the class and
    // automatically injects into the object annotated with @InjectMocks (if
    // possible).
    @Mock
    private RegistrationService registrationService;
    // This @Mock annotation simply creates a mock instance. There is nowhere to
    // inject it. Depending on the particular circumstance, it may be better or
    // clearer to instantiate the mock explicitly in the test itself, but we're
    // doing it here for illustration. Also, I don't know what your real class
    // is like, but it may be more appropriate to just instantiate a real one
    // than a mock one.
    @Mock
    private ModelMap model;
    // Same as above
    @Mock
    private BulkRegistration bulkRegistration;
    // Same as above
    @Mock
    private FileData fileData;

    @Before
    public void setUp() {
        // We want to make sure that when we call getFileData(), it returns
        // something non-null, so we return the mock of fileData.
        when(bulkRegistration.getFileData()).thenReturn(fileData);
    }

    /**
     * This test very narrowly tests the correct next page. That is why there is
     * so little expectation setting on the mocks. If you want to test other
     * things, such as behavior when you get an exception or having the expected
     * filename, you would write other tests.
     */
    @Test
    public void testCreate() throws Exception {
        final String target = "bulkRegistration";
        // Here we create a default instance of BindingResult. You don't need to
        // mock everything.
        BindingResult result = new BindingResult();

        String nextPage = null;
        // Perform the action
        nextPage = controllerUT.create(bulkRegistration, result, model);
        // Assert the result. This test fails, but it's for the right reason -
        // you expect "bulkRegistration", but you get "registration".
        assertEquals("Controller is not requesting the correct form", nextPage,
                target);

    }

    /**
     * Here is a simple example to simulate an exception being thrown by one of
     * the collaborators.
     * 
     * @throws Exception
     */
    @Test(expected = NumberFormatException.class)
    public void testCreateWithNumberFormatException() throws Exception {
        doThrow(new NumberFormatException()).when(registrationService)
                .processFile(any(File.class), anyList());
        BindingResult result = new BindingResult();
        // Perform the action
        controllerUT.create(bulkRegistration, result, model);
    }
}

绝对可以通过嘲笑它们与Mockito（或JMock）的依赖关系来为Spring MVC控制器编写纯单元测试，如jherricks上面所示。仍然存在的挑战是，对于带注释的POJO控制器，还有很多内容尚未经过测试 - 基本上，在调用控制器时，在注释中表达并由框架完成的所有内容。

对测试Spring MVC控制器的支持正在进行中（参见spring-test-mvc项目）。虽然该项目仍将进行更改，但它可以以当前形式使用。如果你对变化很敏感，但你不应该依赖它。无论哪种方式，我都觉得如果你想跟踪它或参与它的发展，都值得指出。有一个夜间快照，如果您想锁定特定版本，本月将有一个里程碑式的版本。