抽象类中的模拟时钟抛出NullPointerException

Question

I have an abstract class like this

public abstract class MyClass {
 final Clock clock;

 Myclass(Clock clock) {
 this.clock = clock;
 }

 public void myMethod() {
   Long time = clock.now().getMillis(); // I get exception here.
   return true;
 }

}

Now I'm writing tests like this:

class MyClassExtender extends MyClass {
  Myclass(Clock clock) {
    super(clock);
  }
}

In the same file

public class MyClassTest {

  private static final Long NOW = "283748L";

  @Rule
  public final Mocks mocks = new Mocks(this);

  @Mock
  private Clock clockMock;

  private myObject = new MyClassExtender(clockMock);

  @Before
  @SuppressWarnings("unchecked")
  public void setup() throws Exception {
    myClassSpy = Mockito.spy(myObject);
  }

  public void testMethod() {
    Mockito.when(clockMock.now().getMillis()).thenReturn(NOW);
    assertThat(myClassSpy.myMethod()).isTrue();
  }
}

This throws a NullPointerException at the line I've mentioned above. What am I doing wrong ? FYI: The now() returns an 'Instant' class object.

Answer 1

Do you use proper runner, ie. MockitoJUnitRunner?

However I believe that clockMock is initialized only after object creation, ie. your myObject will receive null as parameter.

Try to initialize myObject only in @Before section.