How to use notToString method of org.mockito.internal.matchers.MatchersToStringTest class

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

This could be achieved by PowerMockito framework.

import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)
@PrepareForTest(SomeClass.class)
public class SomeClassTest {

    private SomeClass someInstance;

    @Before
    public void setUp() throws Exception {

        someInstance = PowerMockito.spy(new SomeClass());
    }

    @Test
    public void sendRequest() throws Exception {

        String json = "JSON";
        String text = "Some text";
        int messageId = 1;

        PowerMockito.doReturn(true).when(someInstance, "isMethod");
        PowerMockito.doReturn(messageId).when(someInstance, "getMessageId", json);

        someInstance.sendRequest(json, text);

        PowerMockito.verifyPrivate(someInstance).invoke("isMethod");
        PowerMockito.verifyPrivate(someInstance).invoke("getMessageId", json);
        PowerMockito.verifyPrivate(someInstance).invoke("sendMessage", messageId, text);
    }

}

Since java 8, the compiler type inference have been greatly improved.

Now you could remove the class parameter from the matcher without any compilation warning:

when(implClassMock.executeTask(any())).thenReturn(null);

Note: i have the same compiler failure but only with eclipse. A bug may be ?

For Java 8 and above, it's easy:

when(mock.process(Matchers.anyList()));

For Java 7 and below, the compiler needs a bit of help. Use anyListOf(Class<T> clazz):

when(mock.process(Matchers.anyListOf(Bar.class)));

As stated in the offical documentation, it is possible and sometimes even advised:

Important gotcha on spying real objects!

Sometimes it's impossible or impractical to use when(Object) for stubbing spies. Therefore when using spies please consider doReturn|Answer|Throw() family of methods for stubbing.

But, once again as the doc states:

Stubbing voids requires different approach from when(Object) because the compiler does not like void methods inside brackets...

Is your method void?

Example from the documentation if void:

doAnswer(new Answer() {
    public Object answer(InvocationOnMock invocation) {
        Object[] args = invocation.getArguments();
        Mock mock = invocation.getMock();
        return null;
    }
}).when(mock).someMethod();

Thus, you should use the following code if your method is void:

MyObject spy = spy(myObject);

doAnswer(new Answer<Object>() {
    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        return null;
    }
}).when(spy).notify();   

Or if it is not void:

when(spy.toString()).thenAnswer(new Answer<String>() {
    @Override
    public String answer(InvocationOnMock invocation) throws Throwable {
        return "this";
    }
});

Figured out.

The method being called was a parameterized method, but could not infer the parameter type from the matcher argument (the last argument was of type Class).

Making the explicit call

when(restTemplate.<Long>exchange(isA(URI.class),eq(HttpMethod.POST),isA(HttpEntity.class), eq(Long.class))).thenThrow(new RestClientException(EXCEPTION_MESSAGE));

fixed my problem.

There are a couple of things you could do to improve your code:

1. Switch to slf4j. This will allow you to code to an interface and be agnostic of the logging implementation under the covers (apache log4j in your case).

2. Switching to slf4j will allow you to not have to concatenate strings when passing to the logging framework - example:

   • this statement: LOGGER.debug("The list already has {} entries" + list.size());
   • can be written like this: LOGGER.debug("The list already has {} entries", list.size());

This has the added benefit of making the place holder in the string literal actually work.

3. You are attempting to assert and capture calls to an object indirectly via the the Logging framework. This will be fragile and error prone as you never know what calls will be made internally in the Logging framework. Mock only your direct dependencies.

4. Don't test logging statements. It's not exactly visible behavior of the class and it makes the test fragile and complicated. Plus, treating the logging statements as you would say using an ArrayList (i.e. part of the language) allows them to be fully exercised AND they output info to the console that may be helpful in debugging a failing test. An example of being fragile is, if you change the logging statement to add more info or maybe you add another logging statement to the method, this test could break for no good reason. At the very least don't assert the number of times called as this will be extremely fragile.

All of that said, if you must test the interactions with the Logging framework - here is a modified version of your code that runs and provides the same functionality. This is basically option #3 from the list of improvements -

package com.spring.mockito;

import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

import org.apache.log4j.Logger;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.runners.MockitoJUnitRunner;

import java.util.Arrays;
import java.util.List;

@RunWith(MockitoJUnitRunner.class)
public class AppTest {

    // create a mock of the logger
    @Mock
    private Logger logger;

    private App uut;

    // Not needed - dont test something that gets called through something else
    // @Captor
    // private ArgumentCaptor<LoggingEvent> captorLoggingEvent;

    @Before
    public void setup() {
        // spy the class under test so we can override the logger method to return our mock logger
        uut = spy(new App());
        when(uut.logger()).thenReturn(logger);

        // Not needed test with the mock directly.
        // Logger root = Logger.getRootLogger();
        // root.addAppender(mockAppender);
        // root.setLevel(Level.DEBUG);
    }

    /**
     * I want to test with over 3 elements.
     */
    @Test
    public void testWithOver3Element() {
        List<String> myList = Arrays.asList("value 1", "value 2", "value 3", "value 4");

        List<String> outputList = uut.addToListIfSizeIsUnder3(myList, "some value");

        Assert.assertEquals(4, outputList.size());
        Assert.assertFalse(myList.contains("some value"));
        verify(logger, times(1)).debug("The list already has {} entries4");

        // not needed
        // try {
        // verify(mockAppender, times(1)).doAppend(captorLoggingEvent.capture());
        // } catch (AssertionError e) {
        // e.printStackTrace();
        // }
        //
        // LoggingEvent loggingEvent = captorLoggingEvent.getAllValues().get(0);
        // Assert.assertEquals("The list already has {} entries", loggingEvent.getMessage());
        // Assert.assertEquals(Level.DEBUG, loggingEvent.getLevel());
    }

    public static class App {
        private static final Logger LOGGER = Logger.getLogger(App.class);

        public List<String> addToListIfSizeIsUnder3(final List<String> list, final String value) {
            if (list == null) {
                logger().error("A null list was passed in");
                return null;
            }
            if (list.size() < 3) {
                list.add(value);
            } else {
                // if you use slf4j this concatenation is not needed
                logger().debug("The list already has {} entries" + list.size());
            }
            return list;
        }

        // make a package private method for testing purposes to allow you to inject a mock
        Logger logger() {
            return LOGGER;
        }
    }
}

You can also look at packages like PowerMockito for mocking statics - but only if absolutely needed.

Hope this helps.

I think

Mockito.reset(wareHouseSpy)

would do it.

Matchers.any(Class) will do the trick:

Mockito.when(object.doThings(Matchers.any(MyEnum.class), Matchers.anyLong()))
    .thenReturn(123L);

null will be excluded with Matchers.any(Class). If you want to include null you must use the more generic Matchers.any().

As a side note: consider using Mockito static imports:

import static org.mockito.Matchers.*;
import static org.mockito.Mockito.*;

Mocking gets a lot shorter:

when(object.doThings(any(MyEnum.class), anyLong())).thenReturn(123L);