How to use returnInt method of org.mockitousage.stubbing.StubbingReturnsSelfTest class

According to docs, this is deprecated. You should use factory method forClass(Class) to create captors instead to avoid NullPointerExceptions. see here

Example:

  ArgumentCaptor<Person> argument = ArgumentCaptor.forClass(Person.class);
  verify(mock).doSomething(argument.capture());
  assertEquals("John", argument.getValue().getName());

You have to use PowerMock and Mockito together.

I don't understand what your code snippet is trying to do, but the following snippets allow the static getInstance() method of the Calendar class to return a mocked Calendar Object. Maybe that'll point you in the right direction

At the class level:

@RunWith(PowerMockRunner.class)
@PrepareForTest(Calendar.class)
public class XXXXXX {

In your test method:

PowerMockito.mockStatic(Calendar.class);
    Calendar calendar = mock(Calendar.class);
    when(calendar.get(eq(Calendar.HOUR_OF_DAY))).thenReturn(3);

    Mockito.when(Calendar.getInstance()).thenReturn(calendar);

Try View -> Tool Windows -> Maven projects, then click the blue icon in the top left of the tool window (Reimport all Maven projects). You should be able to find the dependencies in the project view, under external libraries.

If this does not work, there is probably something wrong with your maven config (pom.xml). Try mvn clean install from the command line see if it gives any errors.

I'll refer your sentence:

So let's say I introduce a new feature and want to test for bugs. I use mvn test form the command line. Then all the test are run but i think it will take ages for a real application with a lot of tests.

This question you raise here is very important, so I'll try to provide an architectural point of view here without delving into technical implementation.

There are many different kinds of tests. What you're referring to is called an integration test, and not a unit test. The difference between those two that in unit tests you're testing one class and all the rest should be mocked (there are frameworks like EasyMock or Mockito for this).

Unit test has a lot of restrictions:

• You cannot access any external components (web servers, db and so forth)
• Unit tests run only in memory
• They are extremely fast (particle of second).

These tests are very helpful when it comes to testing the functionality of your classes

Now when the development of the feature is done, its time to test that the feature works in "semi-real" environment. Usually when running those, there is a database available as well as spring container. For running this kind of tests you can use spring tests extensions and use different techniques (for example, substitute one the whole application spring context with a "partial" context or override some beans with stubs or something.

Now, this difference is interesting in the context of your question because there should be many unit tests and substantially less integration tests in the application. So if you can cover something you've written with unit tests - write unit tests. It's incredibly fast by nature and you can run a lot of those (thousands) in no-time. Only if you (rarely) cannot cover your functionality in unit tests - write the integration test. This will typically relevant for code that runs against the DB for example and you would like to test whether the queries produced by the component are really valid.

So generally if you have both types of tests you should be covered and there should be not so many integration tests, so running those shouldn't be a real hassle.

Using Mockito, you can do spying on real objects like this:

import org.junit.Test;
import static org.mockito.Mockito.*;
public class MyClassTest {
    @Test
    public void otherMethodShouldBeCalled() {
        MyClass myClass = new MyClass();
        MyClass spy = spy(myClass);

        spy.myMethod(true);
        verify(spy).otherMethod();
    }
}

There are some gotchas, so take a look at the relevant documentation as well.

They both achieve the same result. Using an annotation (@Mock) is usually considered "cleaner", as you don't fill up your code with boilerplate assignments that all look the same.

Note that in order to use the @Mock annotation, your test class should be annotated with @RunWith(MockitoJUnitRunner.class) or contain a call to MockitoAnnotations.initMocks(this) in its @Before method.

When you're using MockK you should not use Mockito.

Only using MockK you can achieve the same with:

val dal = mockk<UserDal> {
    every { insert(any()) } returnsArgument 0
}

If you intend to use Mockito, you should remove MockK and use mockito-kotlin:

val dal = mock<UserDal> {
    on { insert(any()) } doAnswer { it.arguments[0] }
}

In my case, I had a similar issue when I worked with JUnit5

@ExtendWith(MockitoExtension.class)
class MyServiceTest {
...

@InjectMocks
MyService underTest;

@Test
void myMethodTest() {
...
}

underTest was null. The cause of the problem was that I used @Test from JUnit4 package import org.junit.Test; instead JUnit5 import org.junit.jupiter.api.Test;

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.