Java: Junit a class with Inject annotation

Question

@Singleton
public class RealWorkWindow implements WorkWindow {

    @Inject private Factory myFactory;

    public RealWorkWindow (
            LongSupplier longSupplier
    ) {
        defaultWindow = myFactory.create(() -> 1000L);
        workWindow = myFactory.create(longSupplier);
    } 
    ...

如你所见，我正在注入工厂 class（通过 FactoryModuleBuilder 注入）

测试代码

@Test
public class RealWorkWindowTest {
    private RealWorkWindow testWindow;

    @BeforeMethod
    void setup() {
        MockitoAnnotations.initMocks(this);

        testWindow = spy(new RealWorkWindow(() -> 1L));
    }

Factory.py

public interface RealWorkWindowFactory {
    RealWorkWindowFactory create(LongSupplier longSupplier);
}

模块

install(new FactoryModuleBuilder()
                        .implement(WorkWindow.class, RealWorkWindow.class)
                        .build(RealWorkWindowFactory.class));

当我运行测试时 RealWorkWindowTest 测试失败，工厂不存在的 NPE，这是有道理的，因为我不认为注入运行s.

如何在 junit 中使用注入进行测试？或正确模拟？

类似于https://mhaligowski.github.io/blog/2014/05/30/mockito-with-both-constructor-and-field-injection.html

中描述的问题

但我遇到的问题是 mock 使用了 IN 构造函数，因此在实例化测试对象时它仍然为空（因为我还没有调用 Mockito.init )

Answer 1

如果您使用 MockitoJUnitRunner，您可以使用 @Mock 为工厂创建模拟并注入它。

@RunWith(MockitoJUnitRunner.class)
public class MyTest {

    @Mock
    private Factory myFactory;

    @InjectMocks
    private RealWorkWindow realWorkWindow;

    @Test
    public void testSomething() {
        when(myFactory.create(/* insert param here */)).thenReturn(/* insert return value here */);

        /* perform your test */
    }
}

Answer 2

使用`@Assisted`注入时使用构造函数注入

Guice 的 Assisted Injection wiki page 提及：

AssistedInject generates an implementation of the factory class automatically. To use it, annotate the implementation class' constructor and the fields that aren't known by the injector:

以后：

AssistedInject maps the create() method's parameters to the corresponding @Assisted parameters in the implementation class' constructor. For the other constructor arguments, it asks the regular Injector to provide values.

因为它们只在那个时候可用，Guice 只会在构造函数调用之后注入字段。这意味着 你必须使用构造函数注入 ，而不是其他机制（除非你有允许 @PostConstruct 或类似的扩展）。

所以让我们根据那个重写你的代码。将你的RealWorkWindow写成如下：

@Singleton public class RealWorkWindow implements WorkWindow { private final WorkWindow defaultWindow; private final WorkWindow workWindow; @Inject public RealWorkWindow(Factory myFactory, @Assisted LongSupplier longSupplier) { defaultWindow = myFactory.create(() -> 1000L); workWindow = myFactory.create(longSupplier); } }

然后您的代码可以变得可测试，如下所示：

@RunWith(MockitoJunitRunner.class) public class RealWorkWindowTest { @Mock Factory myFactory; @Mock WorkWindow defaultWindow; @Mock WorkWindow workWindow; RealWorkWindow realWorkWindow; @BeforeEach void setup() { when(myFactory.create(any(LongSupplier.class))) .thenReturn(defaultWindow) // First call .thenReturn(workWindow); // Second call realWorkWindow = new RealWorkWindow(myFactory, () -> 1000L); } }

Java: Junit a class with Inject annotation