How to use shouldKnowWhenActualArgsSizeIsDifferent method of org.mockito.internal.invocation.InvocationsFinderTest class

I think

Mockito.reset(wareHouseSpy)

would do it.

Solution:

Mockito.doReturn(value)
       .when(mockObject)
       .myMethod(Mockito.any(MyExecutionContext‌​.class))

You may want to try mockito. The test works like this:

You use mockito to "implement" EntityManager. Instead of the real code, you use the methods of mockito to say "if the application calls getReference(), then return this object". In the background, mockito will create a proxy instance which intercepts the Java method calls and returns the values which you specify. Calls to other methods will return null.

Mocking things like createQuery() works the same way but you first need to create a mockup of Query and then use the same approach as in getReference() (return the query mockup).

Since you don't use a real EM, you don't need a real persistence.xml.

A much more simple solution would be if you could set some property to change the name of the persistence.xml file but I don't think that this is possible.

Some other links that may help:

• How to configure JPA for testing in Maven
• Suggest a JPA Unit test framework

You must use PowerMockito.spy() instead of Mockito.spy()!

Try to import static org.powermock.api.mockito.PowerMockito.spy;

Mockito requires you to either use only raw values or only matchers when stubbing a method call. The full exception (not posted by you here) surely explains everything.

Simple change the line:

when(jdbcTemplate.queryForObject(anyString(), any(SqlParameterSource.class), String.class
                        )).thenReturn("Test");

to

when(jdbcTemplate.queryForObject(anyString(), any(SqlParameterSource.class), eq(String.class)
                        )).thenReturn("Test");

and it should work.

To verify the number of times it was invoked, use verify(spiedObject, times(x)).doSomething().

You should NOT be verifying the value returned from the spied object. It is not the object under test so why verify what it returns. Instead verify the behavior of the object under test in response to the value returned from the spy.

Also, if you don't KNOW what value will be returned by the spied object it would be better to use a mock instead of a spy.

The problem with your unit-test is, that you are trying to mock a method of your actual class which you want to test but you can't actually invoke a mock method as this will return null unless you declare a mocked return value on that invoked method. Usually, you only mock external dependencies.

There are actually two ways to create test-objects: mock and spy. The primer one will create a new object based on the class you provided which has internal state null and also return null on every invoked method. That's why you need to define certain return values for method invocations. spy on the other hand creates a real object and intercepts method invocations if "mock definitions" are defined for certain methods.

Mockito and PowerMock provide two ways of defining your mocked methods:

// method 1
when(mockedObject.methodToMock(any(Param1.class), any(Param2.class),...)
    .thenReturn(answer);
when(mockedObject, method(Dependency.class, "methodToMock", Parameter1.class, Parameter2.class, ...)
    .thenReturn(answer);

or

// method 2
doReturn(answer).when(mockedObject).methodToMock(param1, param2);

The difference is, that the method 1 will execute the methods implementation while the later one won't. This is important if you deal with spy objects as you sometimes don't want to execute the real code inside the invoked method but instead just replace the code or return a predefined value!

Although Mockito and PowerMock provide a doCallRealMethod() which you can define instead of doReturn(...) or doThrow(...), this will invoke and execute the code within your real object and ignores any mocked method return statements. Though, this is not that useful in your case where you want to mock a method of your class under test.

A method implementation can be "overwritten" by

doAnswer(Answer<T>() { 
    @Override 
    public T answer(InvocationOnMock invocation) throws Throwable {
        ...
    }
)

where you simply can declare what the logic of the invoked method should be. You can utilize this to return the mock result of the protected method therefore like this:

import static org.hamcrest.core.IsSame.sameInstance;
import static org.junit.Assert.assertThat;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.spy;
import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.doAnswer;
import static org.mockito.Matchers.any;
import static org.mockito.Matchers.anyString;

import java.io.InputStream;

import org.junit.Test;
import org.mockito.invocation.InvocationOnMock;
import org.mockito.stubbing.Answer;

public class FooKeyRetrieverTest {

    @Test
    public void testGetFooKey() throws Exception {
        // Arrange
        final FooKeyRetriever sut = spy(new FooKeyRetriever());
        FooKey mockedKey = mock(FooKey.class);

        doReturn(mockedKey)
            .when(sut).getKeyFromStream(any(InputStream.class), anyString());
        doAnswer(new Answer<FooKey>() {

            public FooKey answer(InvocationOnMock invocation) throws Throwable {
                return sut.getKeyFromStream(null, "");
            }
        }).when(sut).getKey(anyString());

        // Act
        FooKey ret = sut.getKey("test");

        // Assert
        assertThat(ret, sameInstance(mockedKey));
    }
}

The code above works, however note that this has the same semantic as simply declaring a return value for the getKey(...) as

doReturn(mockedKey).when(sut).getKey(anyString());

Trying to modify only getKeyFromStream(...) with something like this:

doReturn(mockedKey)
    .when(sut).getKeyFromStream(any(InputStream.class), anyString());

without modifying getKey(...) of your System-Under-Test (SUT) won't achieve anything as the real code of getKey(...) would be executed. If you however mock the sut-object, you could not invoke the method in your // Act section as this would return null. If you try

doCallRealMethod().when(sut).getKey(anyString());

on a mock object, the real method woulb be called and as mentiond beforehand, this would also invoke the real implementations of getKeyFromStream(...) and getKeyStream(...) regardless what you specified as mock-method.

As you probably can see by yourself, mocking methods of your actual class under test is not that useful and puts more burden to you than it provides any good. Therefore, it's up to you or your enterprise' policy if you want or need to test private/protected methods at all or if you stick to testing only the public API (which I would recommend). You also have the possibility to refactor your code in order to improve testability although the primary intent of refactoring should be to improve the overall design of your code.

ExpectedException works by wrapping your entire test method in a try-catch block via a JUnit @Rule. When your code throws an exception, it goes up the stack to the nearest try/catch, which happens to be in the ExpectedException instance (which checks that it is the exception you're expecting).

In Java, if an uncaught exception occurs in a method, control will never return to statements later in that method. The same rules apply here: Control never returns to the statements in your test after the exception.

Technically, you could put the verifications in a finally block, but that tends to be a bad habit. EDIT: Your system-under-test might throw an unexpected exception, or no exception at all, which would give you a helpful failure message and trace; however, if that failure then causes your verifications or assertions to fail in the finally block, then Java will show that rather than a message about the unexpected exception or unexpected success. This can make debugging difficult, especially because your error will come from lines of code following the root cause of the error, incorrectly implying that the code above it succeeded.

If you really need to verify state after the exception, on a per-method basis, you can always revert back to this idiom:

@Test
public void testExpectedException()
{
  MockedObject mockObj = mock(MockedObj.class);
  MySubject subject = new MySubject(mockedObj);
  try {
    subject.someMethodThrowingException();
    fail("Expected MyException.");
  } catch (MyException expected) {
    assertEquals("My exception message.", expected.getMessage());
  }
  verify(mockObj).someCleanup(eq(...));
}

Update: With Java 8's lambda expressions, you can wrap a functional interface call in a try block concisely enough to be useful. I imagine support for this syntax will find its way into many standard testing libraries.

assertThrows(MyException.class,
    () -> systemUnderTest.throwingMethod());

The thenReturn() method signature is

thenReturn(T value, T... values)

So it takes an instance of T, followed by a vararg T..., which is syntactic sugar for an array. So you can use

when(foo.bar()).thenReturn(list.get(0), 
                           list.subList(1, list.size()).toArray(new Foo[]{}));

But a cleaner solution would be to create an Answer implementation that takes a List as argument and answers the next element of the list every time it's used. And then use

when(foo.bar()).thenAnswer(new SequenceAnswer<>(list));

For example:

private static class SequenceAnswer<T> implements Answer<T> {

    private Iterator<T> resultIterator;

    // the last element is always returned once the iterator is exhausted, as with thenReturn()
    private T last;

    public SequenceAnswer(List<T> results) {
        this.resultIterator = results.iterator();
        this.last = results.get(results.size() - 1);
    }

    @Override
    public T answer(InvocationOnMock invocation) throws Throwable {
        if (resultIterator.hasNext()) {
            return resultIterator.next();
        }
        return last;
    }
}