How to use getStrictness method of org.mockito.internal.stubbing.StubbedInvocationMatcher class

You need to put the class where the constructor is called into the @PrepareForTest annotation instead of the class which is being constructed - see Mock construction of new objects.

In your case:

✗ @PrepareForTest(MyQueryClass.class)

✓ @PrepareForTest(A.class)

More general:

✗ @PrepareForTest(NewInstanceClass.class)

✓ @PrepareForTest(ClassThatCreatesTheNewInstance.class)

Well yes - the actual code of Foo doesn't matter, because you're mocking it... and Mockito doesn't know there's meant to be a relationship between setName and getName. It doesn't assume that it should store the argument to setName and return it when getName is called... it could do that, but it doesn't as far as I'm aware. The mock provided by Mockito just allows you to specify what happens when methods are called on it, and check what was called later on. Instead of calling setName, you could mock a call to getName() and specify what it should return...

... or you could just use Foo directly instead of mocking it. Don't think you have to mock everything in your tests. Just mock (or fake) things that are awkward when you're using the real class, e.g. because it uses the file system or network.

(I assume you can use Mockito though) Nothing dedicated comes to my mind but I tend to use the following strategy when it comes to situations like that:

1) In the class under test, replace the static direct call with a call to a package level method that wraps the static call itself:

public class ToBeTested{

    public void myMethodToTest(){
         ...
         String s = makeStaticWrappedCall();
         ...
    }

    String makeStaticWrappedCall(){
        return Util.staticMethodCall();
    }
}

2) Spy the class under test while testing and mock the wrapped package level method:

public class ToBeTestedTest{

    @Spy
    ToBeTested tbTestedSpy = new ToBeTested();

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

    @Test
    public void myMethodToTestTest() throws Exception{
       // Arrange
       doReturn("Expected String").when(tbTestedSpy).makeStaticWrappedCall();

       // Act
       tbTestedSpy.myMethodToTest();
    }
}

Here is an article I wrote on spying that includes similar case, if you need more insight: sourceartists.com/mockito-spying

Use one, or more, ArgumentCaptors.

It is unclear what your types are here, but anyway. Let's suppose you have a mock which has a method doSomething() taking a Foo as an argument, then you do this:

final ArgumentCaptor<Foo> captor = ArgumentCaptor.forClass(Foo.class);

verify(mock).doSomething(captor.capture());

final Foo argument = captor.getValue();

// Test the argument

Also, it looks like your method returns void and you don't want it to do anything. Just write this:

doNothing().when(theMock).doSomething(any());

@Mock creates a mock. @InjectMocks creates an instance of the class and injects the mocks that are created with the @Mock (or @Spy) annotations into this instance.

Note you must use @RunWith(MockitoJUnitRunner.class) or Mockito.initMocks(this) to initialize these mocks and inject them (JUnit 4).

With JUnit 5, you must use @ExtendWith(MockitoExtension.class).

@RunWith(MockitoJUnitRunner.class) // JUnit 4
// @ExtendWith(MockitoExtension.class) for JUnit 5
public class SomeManagerTest {

    @InjectMocks
    private SomeManager someManager;

    @Mock
    private SomeDependency someDependency; // this will be injected into someManager
 
     // tests...

}

I solved in this way:

@Spy Response response;

...

// for assignments in code under testing:
doReturn( response ).when( dwConnector ).getResource( anyString() );

// for entity and response status reading:
doReturn( "{a:1}".getBytes() ).when( response ).readEntity( byte[].class );
doReturn( 200 ).when( response ).getStatus();

You can just write

verify(service).perform((Collection<String>) Matchers.argThat(contains("a", "b")));

From the compiler's point of view, this is casting an Iterable<String> to a Collection<String> which is fine, because the latter is a subtype of the former. At run time, argThat will return null, so that can be passed to perform without a ClassCastException. The important point about it is that the matcher gets onto Mockito's internal structure of arguments for verification, which is what argThat does.

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"));
}

"Mock" your repository method calls. Also, use @InjectMocks instead @Autowired for TransactionService. And you can also use MockitoJUnitRunner. How to mock repository calls:

when(customerRepository.save(sender)).thenReturn(someSenderInstance);

To verify that mocked method call has been invoked use:

verify(customerRepository, times(1)).save(sender);

Also, remember one thing: You are testing services! Therefore, all calls to database should be mocked.