使用Mockito时，如何验证某些其他对象

Question

我有以下我要测试的Java代码。我遇到的困难是弄清楚如何验证对handleAppVersionRequest的调用，实际上构建了AppVersionResponse对象。有什么方法可以使用Mockito？

这里的代码是方法：

class MyClass {
        public void handleAppVersionRequest(String dataStr, 
    final int dataChannelId) {
            String ver = "1.0";
            final AppVersionResponse resp = new AppVersionResponse(ver);
            Timber.d("Sending data %s", resp.toString());
            sendResponse(dataChannelId, getGson().toJson(resp));
        }
}

这是测试的方法：

@Test
public void testHandleAppVersionRequest() throws Exception {
    MyClass presenter = Mockito.spy(new MyClass());
    String versionRequestJson = "{"command":1}";
    when(presenter.getGson()).thenReturn(gSon);
    presenter.handleAppVersionRequest(versionRequestJson,0);
    // How do I verify that AppResponse object was constructed?
    verify(presenter,times(1)).sendResponse(anyInt(),anyString());
}

Answer 1

如果您必须在单元测试期间测试对象的创建，则可以提取工厂，对其进行模拟测试，然后验证create方法是在其中调用的。

同时，考虑花一些时间来查看一些嘲讽和单位测试的教程，例如这样。您应该选择一个将是"正在测试的系统"的类。不要间谍或嘲笑这堂课！相反，将模拟作为依赖项，您将用来测试类的行为。

这是从您的MyClass提取的工厂：

class AppVersionResponseFactory {
    AppVersionResponse create(String version) {
        return new AppVersionResponse(version);
    }
}

然后

class MyClass {
    //dependencies that can now be mocked!
    private final AppVersionResponseFactory appVersionResponseFactory;
    private final Gson gson;
    //pass the mockable dependencies in the constructor of the system under test!
    public MyClass(AppVersionResponseFactory appVersionResponseFactory, Gson gson) {
        this.appVersionResposeFactory = factory;
        this.gson = gson;
    }
    public void handleAppVersionRequest(String dataStr, final int dataChannelId) {
        String ver = "1.0";
        AppVersionResponse resp = AppVersionResponseFactory.create(ver);
        Timber.d("Sending data %s", resp.toString());
        sendResponse(dataChannelId, gson.toJson(resp));
    }
}

现在您的测试看起来像这样：

//mocks
AppVersionResponseFactory mockAppVersionResposeFactory;
Gson mockGson;
//system under test
MyClass myClass;
@Before
public void setUp() {
    mockAppVersionResposeFactory = Mockito.mock(AppVersionResponseFactory.class);
    mockGson = Mockito.mock(Gson.class);
    myClass = new MyClass(mockGson, mockAppVersionResposeFactory);
}
@Test
public void testHandleAppVersionRequest() throws Exception {
    String versionRequestJson = "{"command":1}";
    myClass.handleAppVersionRequest(versionRequestJson, 0);
    verify(appVersionResposeFactory).create("1.0");
}

请注意，尽管您的问题要求一种验证对象构造的方法，但更好的测试可能会测试该方法的最终结果，即使用正确的Datachannelid和正确的JSON调用了SendResponse。您可以在此答案中使用相同的技术来完成，即提取依赖项（也许是ResponseSender？），将其传递到MyClass的构造函数中，在测试中对其进行模拟，然后在其上调用验证。

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