如何在Spring MVC应用程序中测试Aspect

Question

我有一个Spring MVC应用程序，在其中我使用Aspect来捕获所有控制器方法中的异常

@Component
@Aspect
public class ControllerExceptionAspect {

    private Logger logger;

    public ControllerExceptionAspect() {
       logger = Logger.getLogger(ControllerExceptionAspect.class);
    }

    public ControllerExceptionAspect(Logger logger) {
       this.logger = logger;
    }

    // Catching all exceptions from all methods in all controllers classes

    @AfterThrowing(pointcut = "execution(* com.my.package..controller..*(..))", throwing = "exception")
    public void afterThrowingAdvice(Exception exception) {
       logger.error("CONTROLLER ASPECT: EXCEPTION IN METHOD -> " +    
       exception.getClass());
    }
}

Aspect可以正常工作，但是很遗憾，我无法对其进行测试。我尝试了很多次，但是在Controller中模拟异常后却无法获取如何捕获Aspect方法的信息

@SuppressWarnings("ALL")
@RunWith(SpringJUnit4ClassRunner.class)
@WebAppConfiguration
@ContextHierarchy({
        @ContextConfiguration(classes = RootConfig.class),
        @ContextConfiguration(classes = WebConfig.class)
})
public class ControllerExceptionAspectTest {

    @Autowired
    ApplicationContext applicationContext;

    @Test
    public void testControllerExceptionAspectGetsExecutedWhenExceptionOccures(){
        HomeController homeController = (HomeController)applicationContext.getAutowireCapableBeanFactory().getBean("homeController");
        try{homeController.callMethod("00000");}
        catch (Exception e){}
        ControllerExceptionAspect controllerExceptionAspect = (ControllerExceptionAspect)applicationContext.getAutowireCapableBeanFactory().getBean("controllerExceptionAspect");
        // HOW TO CATCH THAT ASPECT METHOD WAS CALLED???
    }
}

Answer 1

在没有整个 Web 上下文（或根本没有任何上下文）的情况下，单独测试一个方面（包括其切入点表达式）非常容易。

我将首先尝试给出一个通用示例，而不是 OP 问题中的示例。

假设我们有一个方面，如果方法的第一个参数为空，则必须抛出异常，否则允许方法调用继续。

它应该只应用于用我们的自定义@ThrowOnNullFirstArg注释注释的控制器。

@Aspect
public class ThrowOnNullFirstArgAspect {
    @Pointcut("" +
            "within(@org.springframework.stereotype.Controller *) || " +
            "within(@(@org.springframework.stereotype.Controller *) *)")
    private void isController() {}

    @Around("isController()")
    public Object executeAroundController(ProceedingJoinPoint point) throws Throwable {
        throwIfNullFirstArgIsPassed(point);
        return point.proceed();
    }

    private void throwIfNullFirstArgIsPassed(ProceedingJoinPoint point) {
        if (!(point.getSignature() instanceof MethodSignature)) {
            return;
        }

        if (point.getArgs().length > 0 && point.getArgs()[0] == null) {
            throw new IllegalStateException("The first argument is not allowed to be null");
        }
    }
}

我们可以这样测试：

public class ThrowOnNullFirstArgAspectTest {
    private final ThrowOnNullFirstArgAspect aspect = new ThrowOnNullFirstArgAspect();
    private TestController controllerProxy;

    @Before
    public void setUp() {
        AspectJProxyFactory aspectJProxyFactory = new AspectJProxyFactory(new TestController());
        aspectJProxyFactory.addAspect(aspect);

        DefaultAopProxyFactory proxyFactory = new DefaultAopProxyFactory();
        AopProxy aopProxy = proxyFactory.createAopProxy(aspectJProxyFactory);

        controllerProxy = (TestController) aopProxy.getProxy();
    }

    @Test
    public void whenInvokingWithNullFirstArg_thenExceptionShouldBeThrown() {
        try {
            controllerProxy.someMethod(null);
            fail("An exception should be thrown");
        } catch (IllegalStateException e) {
            assertThat(e.getMessage(), is("The first argument is not allowed to be null"));
        }
    }

    @Test
    public void whenInvokingWithNonNullFirstArg_thenNothingShouldBeThrown() {
        String result = controllerProxy.someMethod(Descriptor.builder().externalId("id").build());
        assertThat(result, is("ok"));
    }

    @Controller
    @ThrowOnNullFirstArg
    private static class TestController {
        @SuppressWarnings("unused")
        String someMethod(Descriptor descriptor) {
            return "ok";
        }
    }
}

关键部分在setUp()方法内部。请注意，它还允许验证切入点表达式的正确性。

如何测试切面方法实际被调用？

如果aspect方法只有一些难以在测试中验证的效果，您可以使用像Mockito这样的模拟库并围绕您的真实aspect制作存根，然后验证该方法是否被实际调用。

private ControllerExceptionAspect aspect = Mockito.stub(new     ControllerExceptionAspect());

然后在您的测试中，通过代理调用控制器后

Mockito.verify(aspect).afterThrowingAdvice(Matchers.any());

如何测试切面方法实际写入日志？

如果您正在使用 logback-classic，您可以编写一个Appender实现并将其添加到Logger感兴趣的内容中，然后检查您期望的消息是否被记录。

public class TestAppender extends AppenderBase<ILoggingEvent> {
    public List<ILoggingEvent> events = new ArrayList<>();

    @Override
    protected void append(ILoggingEvent event) {
        events.add(event);
    }
}

在夹具设置中：

appender = new TestAppender();
// logback Appender must be started to accept messages
appender.start();
ch.qos.logback.classic.Logger logger = (ch.qos.logback.classic.Logger) LoggerFactory.getLogger(ControllerExceptionAspect.class.class);
logger.addAppender(appender);

并在您的测试中：

List<ILoggingEvent> errors = appender.events.stream()
        .filter(event -> event.getLevel() == Level.ERROR)
        .collect(Collectors.toList());
assertEquals("Exactly one ERROR is expected in log", 1, errors.size());
// any other assertions you need

也许你还需要stop()在Appender中@After的方法，但我不知道。

Answer 2

我认为您想要实现的是测试您创建的配置（方面切入点），而不是可以进行单元测试的方面本身。恐怕没有简单的方法可以实现这一目标。

您可以遵循一些有关捕获日志或其他想法的互联网建议。老实说，仅当您确实需要测试Aspect的预期行为时，我才对其进行测试。如果正在记录日志，我不会这样做。如果它为数据库设置了某些内容（或其他副作用），我将验证该值是否在数据库中。那就是集成测试的草草地面。

如果确实需要按自己的方式测试方面，则可以编写类似于给定代码的内容。但是请记住，正常的（非测试）运行时Spring配置将需要虚拟存在于Spring上下文中的Verifier接口的虚拟实现。

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(Config.class)
public class AspectTesting {

    @Autowired
    ServiceWithAspect service;

    @Autowired
    Verifier verifyingAspect;

    @Test
    public void test() {
        // given
        boolean condition = false;

        // when
        try {
            service.doit();
        } catch (Exception swallow) {}

        // then
        try {
            condition = ((VerifyingAspect) ((Advised) verifyingAspect).getTargetSource().getTarget()).wasExecuted();
        } catch (Exception swallow) {}

        // then
        Assert.assertTrue(condition);
    }
}

@Configuration
@EnableAspectJAutoProxy
@ComponentScan("aspects")
class Config {
}

@Component
class VerifyingAspect implements Verifier {

    private boolean executed = false;

    public boolean wasExecuted() {
        return executed;
    }

    @Override
    public void invoked() {
        executed = true;
    }
}

@Service
class ServiceWithAspect {
    public void doit() {
        throw new RuntimeException();
    }
}

@Component
@Aspect
class TestedAspect {

    @Autowired
    Verifier verifier;

    @AfterThrowing(pointcut = "execution(* *(..))", throwing = "exception")
    public void afterThrowingAdvice(Exception exception) {
        // your aspect logic here
        verifier.invoked();
    }
}

interface Verifier {
    void invoked();
}