RxJava testing NullPointerException on Schedulers.io()

Question

I have unit test to test user repository and i use custom rule to override the Schedulers and i'm still get the NullPointerException

Here is the test code

public class UserRepositoryTest extends BaseTest {

    @Mock
    private UserMapper userMapper;

    @Mock
    private GithubService githubService;

    @Mock
    private Throwable throwable;

    @InjectMocks
    private UserRepository userRepository;

    @Test
    public void fetchUsersEmitsErrorWhenNetworkServiceErrors() {
        when(githubService.getUsers()).thenReturn(Single.error(throwable));
        userRepository.fetchUsers().test().assertError(throwable);
    }

    @Test
    public void usersRawItemsFromServiceAreMapped() throws Exception {
        List<UserRaw> userRawList = createUserRawList();
        when(githubService.getUsers()).thenReturn(Single.just(userRawList));

        userRepository.fetchUsers().subscribe();

        verify(userMapper).apply(userRawList.get(0));
        verify(userMapper).apply(userRawList.get(1));
        verify(userMapper).apply(userRawList.get(2));
    }

    private static List<UserRaw> createUserRawList() {
        return new ArrayList<UserRaw>() {
            {
                add(mock(UserRaw.class));
                add(mock(UserRaw.class));
                add(mock(UserRaw.class));
            }
        };
    }

}

The base class that the test extend from

@RunWith(MockitoJUnitRunner.StrictStubs.class)
public abstract class BaseTest {

    @Rule
    public final MockitoRule rule = MockitoJUnit.rule();

    @Rule
    public final RxSchedulerOverrideRule overrideSchedulersRule = new RxSchedulerOverrideRule();

}

The custom rule

public class RxSchedulerOverrideRule implements TestRule {

    @Override
    public Statement apply(final Statement base, Description description) {
        return new Statement() {
            @Override
            public void evaluate() throws Throwable {
                RxJavaPlugins.setIoSchedulerHandler(scheduler -> Schedulers.trampoline());
                RxJavaPlugins.setComputationSchedulerHandler(scheduler -> Schedulers.trampoline());
                RxJavaPlugins.setNewThreadSchedulerHandler(scheduler -> Schedulers.trampoline());
                try {
                    base.evaluate();
                } finally {
                    RxJavaPlugins.reset();
                }
            }
        };
    }

}

and the code from the repository code

 public Single<List<User>> fetchUsers() {
        return githubService.getUsers()
                .subscribeOn(Schedulers.io())
                .observeOn(Schedulers.computation())
                .flatMapObservable(Observable::fromIterable)
                .map(userMapper)
                .toList();
    }

I think this bug is very weird because i already override the repository Schedulers

This the message

java.lang.NullPointerException at com.ahmedabdelmeged.githubarch.data.UserRepository.fetchUsers(UserRepository.java:41) at com.ahmedabdelmeged.githubarch.data.UserRepositoryTest.usersRawItemsFromServiceAreMapped(UserRepositoryTest.java:46) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:498) at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47) at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17) at org.mockito.internal.junit.JUnitRule$1.evaluateSafely(JUnitRule.java:63) at org.mockito.internal.junit.JUnitRule$1.evaluate(JUnitRule.java:43) at com.ahmedabdelmeged.githubarch.common.RxSchedulerOverrideRule$1.evaluate(RxSchedulerOverrideRule.java:24)

You didn't show all of your code. In the code you didn't show, you are passing a null pointer into the `fetchUsers()` method. — Bob Dalgleish, Feb 06 '18 at 14:02
ah ok i will add it but the error happen to the two methods i edit the post — Ahmed Abdelmeged, Feb 06 '18 at 14:11

RxJava testing NullPointerException on Schedulers.io()

0 Answers0