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Mariano Eduardo Rodriguez edited this page Nov 6, 2022 · 20 revisions
Mockito

Mockito is a mocking framework for unit tests in Java. It has been designed to be intuitive to use when the test needs mocks.

Installation

      Mockito for Windows

      Mockito for Mac

      Mockito for Linux

  • Simple usage : stub, use, verify
  • Programatic creation of mocks via mock() or spy()
  • Programmatic stubbing via
    • Mockito.when(mock.action()).thenReturn(true)
    • BDDMockito.given(mock.action()).willReturn(true)
  • Customize mock answer or provide your own
  • Programmatic verification via
    • Mockito.verify(mock).action()
    • BDDMockito.then(mock).should().action()
  • Annotation sugar via @Mock, @Spy, @Captor or @InjectMocks
  • JUnit first class support via the runner MockitoJUnitRunner and the now favored rule MockitoJUnit.rule()

Remember

  • Do not mock types you don't own
  • Don't mock value objects
  • Don't mock everything
  • Show some love with your tests

Examples

// You can mock concrete classes and interfaces
TrainSeats seats = mock(TrainSeats.class);

// stubbing appears before the actual execution
when(seats.book(Seat.near(WINDOW).in(FIRST_CLASS))).thenReturn(BOOKED);

// the following prints "BOOKED"
System.out.println(seats.book(Seat.near(WINDOW).in(FIRST_CLASS)));

// the following prints "null" because 
// .book(Seat.near(AISLE).in(FIRST_CLASS))) was not stubbed
System.out.println(seats.book(Seat.near(AISLE).in(FIRST_CLASS)));

// the following verification passes because 
// .book(Seat.near(WINDOW).in(FIRST_CLASS)) has been invoked
verify(seats).book(Seat.near(WINDOW).in(FIRST_CLASS));

// the following verification fails because 
// .book(Seat.in(SECOND_CLASS)) has not been invoked
verify(seats).book(Seat.in(SECOND_CLASS));

The BDD way :

// You can mock concrete classes and interfaces
TrainSeats seats = mock(TrainSeats.class);

// stubbing appears before the actual execution
given(seats.book(Seat.near(WINDOW).in(FIRST_CLASS))).willReturn(BOOKED);

// the following prints "BOOKED"
System.out.println(seats.book(Seat.near(WINDOW).in(FIRST_CLASS)));

// the following prints "null" because 
// .book(Seat.near(AISLE).in(FIRST_CLASS))) was not stubbed
System.out.println(seats.book(Seat.near(AISLE).in(FIRST_CLASS)));

// the following verification passes because 
// .book(Seat.near(WINDOW).in(FIRST_CLASS)) has been invoked
then(seats).should().book(Seat.near(WINDOW).in(FIRST_CLASS));

// the following verification fails because 
// .book(Seat.in(SECOND_CLASS)) has not been invoked
then(seats).should().book(Seat.in(SECOND_CLASS));

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