Spring Mockito cannot mock AspectJ-weaved @Async method

When trying to mock an @Async method from a @SpyBean I get the following error:

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Misplaced or misused argument matcher detected here:

-> at package.TestClass.init_aroundBody0(File.java:79)
-> at package.TestClass.init_aroundBody0(File.java:79)

You cannot use argument matchers outside of verification or stubbing.
Examples of correct usage of argument matchers:
    when(mock.get(anyInt())).thenReturn(null);
    doThrow(new RuntimeException()).when(mock).someVoidMethod(anyObject());
    verify(mock).someMethod(contains("foo"))

This message may appear after an NullPointerException if the last matcher is returning an object 
like any() but the stubbed method signature expect a primitive argument, in this case,
use primitive alternatives.
    when(mock.get(any())); // bad use, will raise NPE
    when(mock.get(anyInt())); // correct usage use

Also, this error might show up because you use argument matchers with methods that cannot be mocked.
Following methods *cannot* be stubbed/verified: final/private/equals()/hashCode().
Mocking methods declared on non-public parent classes is not supported.

This error only appears when I run the test without debugger attached. When I try to debug, the error doesn't show up, and everything works fine. When I remove the @Async, then it works also without the debugger attached.

This error started showing up after I upgraded from spring 4 to spring 5. Using spring-boot-starter-test 2.1.6.RELEASE (mockito-core:2.23.4, spring-test:5.1.8.RELEASE)

Comment From: sbrannen

Due to the involvement of @SpyBean, it sounds to me like it might be an issue in Spring Boot Test.

@philwebb and @wilkinsona, have you come across something like this before?

Comment From: philwebb

We've seen a few issue like this in the past related to AOP. I'll transfer the issue.

Comment From: philwebb

@cdalexndr Could you please provide a sample that shows the problem. Preferably something we can just download or clone and run.

Comment From: spring-projects-issues

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

Comment From: cdalexndr

Test project at: https://github.com/cdalexndr/spring-boot-issue-17593 Just run gradlew test

After some playing with various settings, I found three ways to cause the tests to pass and I've commented them in the code as:

//commenting this line causes test to pass (1 of 3)
//commenting this line causes test to pass (2 of 3)
//commenting this line causes test to pass (3 of 3)

Comment From: mbhave

Thanks for the sample @cdalexndr.

@philwebb @sbrannen This doesn't seem to be Spring Boot specific as using regular mocks and removing @SpringBootTest seems to cause the same behavior. Changing AdviceMode from ASPECTJ to PROXY gets rid of the failure so it doesn't look like it's related to spring-projects/spring-boot#6573.

Comment From: wilkinsona

@mbhave I've tried and failed to reproduce the problem without @SpyBean. Do you still have the code that you used anywhere?

Comment From: mbhave

Sorry, @wilkinsona, I should've copied what I had in the comment above. I used the sample provided above and this is what I'd changed the test to:

@ContextConfiguration(classes = Application.class)
public class Test extends AbstractTestNGSpringContextTests {
    private static final Logger log = LoggerFactory.getLogger( Test.class );

    @Spy
    Service service;

    @BeforeMethod
    public void setUp() {
    MockitoAnnotations.initMocks(this);
    }

    @org.testng.annotations.Test
    public void test() {
        assertTrue( MockUtil.isSpy( service ) );
        doReturn( new CompletableFuture<>() ).when( service ).asyncMethod( any( Integer.class ) );
        doReturn( null ).when( service ).work(); //commenting this line causes test to pass (3 of 3)
        CompletableFuture<Integer> future = service.asyncMethod( 1 );
        log.info( "Success" );
    }
}

Comment From: wilkinsona

The following reproduces the problem:

package example;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.doReturn;

import java.util.concurrent.CompletableFuture;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.MockitoAnnotations;
import org.mockito.Spy;
import org.mockito.internal.util.MockUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.context.annotation.AdviceMode;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.stereotype.Service;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;

@ContextConfiguration(classes = Application.class)
@RunWith(SpringRunner.class)
public class AsyncSpyTests {

    private static final Logger log = LoggerFactory.getLogger(AsyncSpyTests.class);

    @Spy
    ExampleService service;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void test() {
        assertThat(MockUtil.isSpy(this.service)).isTrue();
        doReturn(new CompletableFuture<>()).when(this.service).asyncMethod(any(Integer.class ));
        doReturn(null).when(this.service).work(); // commenting this line causes test to pass
        this.service.asyncMethod(1);
        log.info("Success");
    }

}

@Service
class ExampleService {

    private static final Logger log = LoggerFactory.getLogger( ExampleService.class );

    @Async // commenting this line causes test to pass
    public CompletableFuture<Integer> asyncMethod(Integer param) {
        work();
        return new CompletableFuture<>();
    }

    protected Integer work() {
        log.info("Work");
        return 0;
    }

}

@EnableAutoConfiguration // commenting this line causes test to pass
@ComponentScan
@Configuration
@EnableAspectJAutoProxy
@EnableAsync(mode = AdviceMode.ASPECTJ)
class Application {

}

plugins {
    id 'org.springframework.boot' version '2.2.5.RELEASE'
}

apply plugin: 'java'
apply plugin: 'io.spring.dependency-management'

repositories {
    mavenCentral()
}

dependencies {
    implementation group: 'org.aspectj', name: 'aspectjweaver'
    implementation group: 'org.springframework.boot', name: 'spring-boot-starter-aop'
    implementation 'org.springframework:spring-aspects'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

test {
    File springAgent = configurations.testRuntimeClasspath.filter { f -> f.name.matches("aspectjweaver.*\\.jar") }.iterator().next();
    jvmArgs += ["-javaagent:" + springAgent.absolutePath]
}

Note that AsyncSpyTests is itself not using any Spring Boot functionality but Application is due to its use of @EnableAutoConfiguration. The test passes when this line is commented out so it appears that there is something that Spring Boot is doing that's causing the problem.

Comment From: wilkinsona

Here's a modified version of the code above that reproduces the problem without any involvement from Spring Boot. The key difference is that @EnableAutoConfiguration has been replaced by a TaskExecutor @Bean on the Application class.

package example;

import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.ArgumentMatchers.any;
import static org.mockito.Mockito.doReturn;

import java.util.concurrent.CompletableFuture;

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.MockitoAnnotations;
import org.mockito.Spy;
import org.mockito.internal.util.MockUtil;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.context.annotation.AdviceMode;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
import org.springframework.core.task.TaskExecutor;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableAsync;
import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
import org.springframework.stereotype.Service;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringRunner;

@ContextConfiguration(classes = Application.class)
@RunWith(SpringRunner.class)
public class AsyncSpyTests {

    private static final Logger log = LoggerFactory.getLogger(AsyncSpyTests.class);

    @Spy
    ExampleService service;

    @Before
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void test() {
        assertThat(MockUtil.isSpy(this.service)).isTrue();
        doReturn(new CompletableFuture<>()).when(this.service).asyncMethod(any(Integer.class ));
        doReturn(null).when(this.service).work(); // commenting this line causes test to pass
        this.service.asyncMethod(1);
        log.info("Success");
    }

}

@Service
class ExampleService {

    private static final Logger log = LoggerFactory.getLogger( ExampleService.class );

    @Async // commenting this line causes test to pass
    public CompletableFuture<Integer> asyncMethod(Integer param) {
        work();
        return new CompletableFuture<>();
    }

    protected Integer work() {
        log.info("Work");
        return 0;
    }

}

@ComponentScan
@Configuration
@EnableAspectJAutoProxy
@EnableAsync(mode = AdviceMode.ASPECTJ)
class Application {

    @Bean
    TaskExecutor taskExector() {
        return new ThreadPoolTaskExecutor();
    }

}

Comment From: cdalexndr

Still reproductible with Spring 5.3.3 (re-encountered the bug)

Comment From: snicoll

This looks like a more general problem, see https://github.com/spring-projects/spring-framework/issues/24735#issuecomment-601172062 that has a reproducer for @Cacheable with AspectJ.

Comment From: leogong

I have the same problem. Spy a bean which is a AOP proxy bean, same error occured.

Comment From: DennisGoermannMD

Hello, we have this issue too. Usecase: We want to test the caching. Problem: With a @SpyBean it does not work. The same test runs with an autowired bean. If the Bean is with @SpyBean intialized the values for the cachekey becomes null. Workaround: As workaround, we could use an autowired bean in this case. But if we do so, the (collection of) tests tooks more time. We want to have only one "base" test file with all beans initialized with @SpyBean, so we can mock or not in every test case. The advantage is that no spring context will be reloaded and the tests runs faster.

Comment From: ghilainm

Same issue here. @SpyBean with @Cacheable does not work.