How to use MockInjectionUsingConstructorIssue421Test class of org.mockitousage.annotation package

I think you do need to cast it, but it shouldn't be too bad:

Foo<Bar> mockFoo = (Foo<Bar>) mock(Foo.class);
when(mockFoo.getValue()).thenReturn(new Bar());

Check the Java API for List.
The get(int index) method is declared to throw only the IndexOutOfBoundException which extends RuntimeException.
You are trying to tell Mockito to throw an exception SomeException() that is not valid to be thrown by that particular method call.

To clarify further.
The List interface does not provide for a checked Exception to be thrown from the get(int index) method and that is why Mockito is failing.
When you create the mocked List, Mockito will use the definition of List.class to creates its mock.

The behavior you are specifying with the when(list.get(0)).thenThrow(new SomeException()) doesn't match the method signature in List API, because get(int index) method does not throw SomeException() so Mockito fails.

If you really want to do this, then have Mockito throw a new RuntimeException() or even better throw a new ArrayIndexOutOfBoundsException() since the API specifies that that is the only valid Exception to be thrown.

You need to use mockito-inline version 3.4.0 or higher and remove mockito-core from your dependencies (mockito-inline depends on mockito-core so it will be retrieved automatically).

That way, you will be using mockito static mocking correctly, but it wouldn't solve the exception that you posted.

To fix it, you need to remove all dependencies of powermock as it conflicts with mockito and causes this error

The used MockMaker PowerMockMaker does not support the creation of static mocks

Found out that by changing the Async mode to AspectJ fixed the issue:

@EnableCaching
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(lazyInit = true) 
@EnableAsync(mode = AdviceMode.ASPECTJ) // Changes here!!!
public class Main {
    public static void main(String[] args) {
        new SpringApplicationBuilder().sources(Main.class)
                                    .run(args);
    }
}

I'll accept this as a temporary hackish solution until I understand what's the real root cause of this issue.

You need to replace the code inside the infinite loop with a function.

You then write a unit test for that function.

Try adding this annotation to your Test class:

@PowerMockIgnore("javax.management.*")

Worked for me.

How about

when( method-call ).thenReturn( value1, value2, value3 );

You can put as many arguments as you like in the brackets of thenReturn, provided they're all the correct type. The first value will be returned the first time the method is called, then the second answer, and so on. The last value will be returned repeatedly once all the other values are used up.

Since Mockito 1.9.5+ and Java 8+

You can use a lambda expression, like:

when(myMock.myFunction(anyString())).thenAnswer(i -> i.getArguments()[0]);

Where i is an instance of InvocationOnMock.

For older versions

You can create an Answer in Mockito. Let's assume, we have an interface named MyInterface with a method myFunction.

public interface MyInterface {
    public String myFunction(String abc);
}

Here is the test method with a Mockito answer:

public void testMyFunction() throws Exception {
    MyInterface mock = mock(MyInterface.class);
    when(mock.myFunction(anyString())).thenAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        Object[] args = invocation.getArguments();
        return (String) args[0];
    }
    });

    assertEquals("someString",mock.myFunction("someString"));
    assertEquals("anotherString",mock.myFunction("anotherString"));
}

There are two testing strategies. One is unit testing, i.e. making sure your service works. The other is integration/end-to-end testing, i.e. making sure everything plays nicely together.

You unit test stuff you own, you integration test everything you have. This is a pretty rough example using just your statement, plus some made up stuff where I can't fill in the blanks.

Unit Tests

Using Mockito

PersonRepository personRepository = mock(PersonRepository.class);

@TestSubject
PersonService personService = new PersonService(): 

@Test
public void unitTest() {
    personService.setPersonRepository(personRepository);
    Person person = new Person(1L);
    Person person2 = new Person(1L);

    when(personRepository.returnPerson(1L)).thenReturn(person2); //expect a fetch, return a "fetched" person;

    personService.deleteFromPerson(person);

    verify(personRepository, times(1)).delete(person2); //pretty sure it is verify after call
}

Using EasyMock...

@Mock
PersonRepository personRepository; //assuming it is autowired

@TestSubject
PersonService personService = new PersonService(): 

@Test
public void unitTest() {
    Person person = new Person(1L);
    Person person2 = new Person(1L);

    EasyMock.expect(personRepository.returnPerson(1L)).andReturn(person2); //expect a fetch, return a "fetched" person;
    personRepository.delete(person2);
    EasyMock.expectLastCall(); //expect a delete for person2 we plan to delete
    replayAll();

    personService.deleteFromPerson(person);

    verifyAll(); //make sure everything was called
}

Yes, this test looks like it is written rigidly, but that's really all you're testing in the unit test, anyways. You want the DB to fetch a Person from the database using an argument, hence why there are two Person objects, and you expect to delete that passed Person object, which is why you expect the call. Simple method yields simple test. You basically want to ensure you're interacting with your repository as you expect. Repository could be broken or null in actual implementation, but that doesn't change the fact that your service is implemented correctly.

Integration Tests

On the other hand, if you want to do an integration test, no mocking is used. Instead, you'll need to wire up everything like a test DB and repo. I'll leave that up to you since there's no reference for implementation.

@Test
public void integrationTestForAddAndDelete() {
    Person person = createDummyPersonForInsertion(); //static method that creates a test Person for you
    Person comparePerson;
    //make sure we haven't added the person yet
    Assert.assertNull(personService.getPerson(person));

    //add the Person
    comparePerson = personService.addPerson(person);
    Assert.assertNotNull(personService.getPerson(person));
    //add a rigorous compare method to make sure contents are the same, i.e. nothing is lost or transmuted incorrectly, ignoring ID if that is autogen
    //alternatively, you can create a unit test just for Person
    Assert.assertEquals(person, comparePerson); 

    //remove the Person
    personService.deleteFromPerson(person);
    Assert.assertNull(personService.getPerson(person));

    //test for exception handling when you try to remove a non-existent person;
    personService.deleteFromPerson(person);

    //test for exception handling when you try to remove null
    personService.deleteFromPerson(null);
}

In this case, you want to make sure your repo actually handles all the calls from the service. You know your service works from the unit test, but does the repo work from the service or have you configured something wrong