Android junit presenter with the view right implementation

Question

I am testing my presenter. For some reason, I got nullPointer on MainPresenter class. But I init it in before method. Please let me know what I init wrong. The main logic is to pass the Event object to the presenter and verify that method was called.

    public class MainPresenterTest {

    MainPresenter mainPresenter;

    @Mock
    MainView mainView;

    @Mock
    ApiDataRepository apiDataRepository;

    @Before
    public void initialize(){
        MockitoAnnotations.initMocks(this);
        mainPresenter = new MainPresenter(apiDataRepository, mainView);
    }

    @Test
    public void inflateDataList() {
        String errorMessage = "Error Message";
        UnitApiEvent event = new UnitApiEvent(null,errorMessage);
        mainPresenter.inflateDataList(event);
        verify(mainView, times(1)).showError(errorMessage);
    }

}

Error message

  java.lang.NullPointerException
    at com.rwapp.interviewapp.presenters.MainPresenter.inflateDataList(MainPresenter.java:35)
    at com.rwapp.interviewapp.presenters.MainPresenterTest.inflateDataList(MainPresenterTest.java:40)
    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.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

Presenter

public class MainPresenter {

ApiDataRepository mApiDataRepository;
MainView mMainView;

public MainPresenter(ApiDataRepository mApiDataRepository, MainView mMainView) {
    this.mApiDataRepository = mApiDataRepository;
    this.mMainView = mMainView;
}

/**
 * Getting data for the list on the MainActivity
 */
public void getData() {
    mApiDataRepository.getUnitsData();
}

/**
 * Unpack the response from UnitApi call.
 */
@Subscribe
public void inflateDataList(UnitApiEvent event) {
    if (event.getmData().size() > 0 && event.getmErrorMessage() == null) {
        mMainView.inflateData(event.getmData());
    } else {
        mMainView.showError(event.getmErrorMessage());
    }
}

As we can see in debugger the event is not null

Since the NPE is happening in MainPresenter.java line 35, it would be useful to show this code as well. — Henry, Jun 30 '20 at 06:30
@Henry this part i just added ` if (event.getmData().size() > 0 && event.getmErrorMessage() == null)` — Bo Z, Jun 30 '20 at 06:37
I'd guess that `event.getmData()` returns `null`. So you can't call `size` on it. — Henry, Jun 30 '20 at 06:41
Does this answer your question? [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Henry, Jun 30 '20 at 06:42
@Henry I understand what is nullpointer but i don't understand why it is here — Bo Z, Jun 30 '20 at 06:46
while creating UnitApiEvent, you are passing null as first param — Shalu T D, Jun 30 '20 at 07:11
@BorisRuzanov "but why if it is null its not skip and jump to else?" because a NPE is thrown before. — Henry, Jun 30 '20 at 07:16
event.getMdata() is null, so you try to call event.getMdata().size() so crash — Shalu T D, Jun 30 '20 at 07:29

Android junit presenter with the view right implementation

0 Answers0