java Spring 中的单元测试：将依赖项注入到被测组件中
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Unit test in Spring: injecting a dependency into a component under test
提问by Damian Nadales
I have a very simple rest controller:
我有一个非常简单的休息控制器：
@RestController
public class MyController {
@Autowired
public Logger logger;
The logger dependency gets injected via the following configuration:
记录器依赖项通过以下配置注入：
@Configuration
public class MyConfig {
@Bean
public Logger logger() {
return LoggerFactory.getLogger(MyController.class);
}
If I run the Spring application that contains the controller then everything works fine. However, I cannot manage to achieve this dependency injection when running my unit tests. In this case I have the following test configuration:
如果我运行包含控制器的 Spring 应用程序，则一切正常。但是，在运行单元测试时，我无法实现这种依赖注入。在这种情况下，我有以下测试配置：
@Configuration
@Profile("test")
public class MyTestConfig {
@Bean
public Logger logger() {
return LoggerFactory.getLogger(MyCOntroller.class);
}
And this is the relevant part of my unit tests code:
这是我的单元测试代码的相关部分：
@RunWith(MockitoJUnitRunner.class)
@ContextConfiguration(classes = MyTestConfig.class)
@ActiveProfiles("test")
public class MyContollerTest {
However the logger object does not get "autowired" in MyController(note that I do not want to mock the logger object), which results in a null pointer reference.
但是，记录器对象不会“自动装配” MyController（请注意，我不想模拟记录器对象），这会导致空指针引用。
What am I missing?
我错过了什么？
回答by JB Nizet
A unit test shouldn't use any Spring configuration. You should simply instantiate your component, and inject dependencies (usually fake ones) manually.
单元测试不应使用任何 Spring 配置。您应该简单地实例化您的组件，并手动注入依赖项（通常是假的）。
You used field injection, which makes it a bit harder. With constructor injection, all you would need to do is
您使用了字段注入，这使它变得有点困难。使用构造函数注入，您需要做的就是
Logger logger = LoggerFactory.getLogger(MyController.class);
MyController controller = new MyController(logger);
Mockito can help injecting fake dependencies for you, though, even when using field injection, thanks to the @Mock, @Spyand @InjectMocksannotations:
Mockito 可以帮助您注入虚假的依赖项，即使在使用字段注入时，感谢@Mock,@Spy和@InjectMocks注释：
@Spy
private Logger logger = LoggerFactory.getLogger(MyController.class);
@InjectMocks
private MyController controller;
@Before
public void prepare() {
MockitoAnnotations.initMocks(this);
}
That said, if I'm not mistaken, you're not using @RunWith(SpringJUnit4ClassRunner.class), so your test runner doesn't know anything about Spring, and thus doesn't create or use any Spring configuration.
也就是说，如果我没记错的话，您没有使用@RunWith(SpringJUnit4ClassRunner.class)，因此您的测试运行程序对 Spring 一无所知，因此不会创建或使用任何 Spring 配置。
