PowerMockito Mocked final class gson.fromJson() Returns null

Question

I have this code in main class -

try {
    extraPlayer = gson.fromJson(jsonResponse, ExtraPlayer.class);// this returns null
} catch (Exception e) {
    e.printStacktrace();
}

Here extraPlayer is coming as null I have mocked @Mock Gson gsonMock;

Here ExtraPlayer is a static class.

I have written this test code -

@Test
public void test() {
    String jsonResponse = "{\"status\":\"waiting\",\"no\":\"12\"}";
    when(playerHandlerMock.resetPlayer("someString", "someString", "1",true    
         )).thenReturn(jsonResponse);       
    Gson gsonMock = PowerMockito.mock(Gson.class);
    ExtraPlayer extraPlayer = new ExtraPlayer();
    extraPlayer.setNo("12");
    extraPlayer.setStatus("Waiting");

    PowerMockito.mockStatic(ResetModemResponse.class); // using this for static class but didn't work.

    PowerMockito.when(gsonMock.fromJson(jsonResponse, ExtraPlayer.class)).thenReturn(extraPlayer);

    playerMock.performWaiting();
}

ExtraPlayer.java

public static class ExtraPlayer{

    String no;
    String status;      

    public String getStatus() {
        return status;
    }

    public void setStatus(String status) {
        this.status = status;
    }

    public String getNo() {
        return code;
    }

    public void setNo(String no) {
        this.no = no;
    }

}

I have added these annotations to the test class -

@RunWith(PowerMockRunner.class)
@PrepareForTest(Gson.class)

why extraPlayer is null ? please help/Suggest.

gson is Autowired in main class. in test i am using like this - when(gsonMock.fromJson(jsonResponse, ExtraPlayer.class)).thenReturn(extraPlayer); — jay thakur, Jul 05 '17 at 13:24
no, Gson.java is final class. pkg is - import com.google.gson.Gson; — jay thakur, Jul 05 '17 at 13:32

score 0 · Answer 1 · answered Jul 05 '17 at 13:38

0

If you were to use the standard @Mock and @InjectMocks annotation with mockito, then yes, the framework would take care of the injection of the mock into the class under test (regardless of the existence of the setters etc.).

Another thing is the playerMock, which i assume is the class under test.

Do not mock the class under test, create a normal instance and then inject the dependencies... the performWaiting method does not seem to accept the response String, so you would have to inject that also somehow (unless you left some parts out):

@Test
public void test() {
    // Arrange
    String jsonResponse = "{\"status\":\"waiting\",\"no\":\"12\"}";     
    Gson gsonMock = PowerMockito.mock(Gson.class);
    ExtraPlayer extraPlayer = new ExtraPlayer();
    extraPlayer.setNo("12");
    extraPlayer.setStatus("Waiting");

    PowerMockito.when(gsonMock.fromJson(jsonResponse, ExtraPlayer.class)).thenReturn(extraPlayer);

    Player player = new Player();
    player.setGson(gsonMock);
    player.setResponse(jsonResponse);

    // Act
    player.performWaiting();

    // Assert ...
}

answered Jul 05 '17 at 13:38

Maciej Kowalski

25,605
12
54
63

1

Gson.java is a final class. I was using {@Mock}, {@InjectMock}. but it was throwing error that mockito can't handle final. – jay thakur Jul 05 '17 at 13:47
yes.. thats why u need powermock and inject manually that dependency – Maciej Kowalski Jul 05 '17 at 13:48
can't do {player.setGson(gsonMock);} as setGson is not a method. – jay thakur Jul 05 '17 at 13:48
You need to create one.. a package level one will be sufficient – Maciej Kowalski Jul 05 '17 at 13:55
Not really.. if you cant inject by constructor or a setter and you are using powermock, then you are left with manual injection by reflection. – Maciej Kowalski Jul 05 '17 at 14:08
by "manual injection by reflection" , do you mean {@Autowired} {@Mock} {@InjectMock} ? – jay thakur Jul 05 '17 at 14:47
Nope, i meant the raw java reflection api. – Maciej Kowalski Jul 05 '17 at 14:52
ohk. I used { @Mock Gson gsonMock;} now gson is not null. but explayer is null here - extraPlayer = gson.fromJson(jsonResponse, ExtraPlayer.class); – jay thakur Jul 05 '17 at 15:03
any suggestion nw ? one thing - ExtraPlayer.class is a static class. – jay thakur Jul 05 '17 at 15:05
do you pass `jsonResponse` into the method? – Maciej Kowalski Jul 05 '17 at 15:11
passing json like this - when(gsonMock.fromJson(jsonResponse, ExtraPlayer.class)).thenReturn(extraPlayer); – jay thakur Jul 05 '17 at 15:14
this is a set-up.. When you invoke player.performWaiting();.. it does not accept the response, so how do you expect to have it passed to the gson call? – Maciej Kowalski Jul 05 '17 at 15:16
Sry, it is like this - when(playerHandlerMock.resetPlayer("someString", "someString", "1", true)).thenReturn(jsonResponse); – jay thakur Jul 05 '17 at 15:23
debugged , jsonResponse is coming fine there. it seems somewhere problem with ExtraPlayer static class. need to mock in test class ? if y, hw ? – jay thakur Jul 05 '17 at 15:25
There is no such thing as a static class.. there can be methods or fields. Try to add all the code related to the case.. i have a feeling you did not post everything. Otherwise the analysis does not make sense – Maciej Kowalski Jul 05 '17 at 15:42
ExtraPlayer is a simple POJO class inside the main class. – jay thakur Jul 05 '17 at 15:47
shouldnt matter.. is the String exaclty the same as in the set-up? – Maciej Kowalski Jul 05 '17 at 16:02
there are some more setters & getters. thats it. – jay thakur Jul 05 '17 at 16:04
can you please suggest, how to do this with reflection ? – jay thakur Jul 05 '17 at 16:21
just try one of the answers on stack: https://stackoverflow.com/questions/32716952/set-private-field-value-with-reflection – Maciej Kowalski Jul 05 '17 at 17:15

PowerMockito Mocked final class gson.fromJson() Returns null

1 Answers1