Setting up greenDAO session object for a junit test

Question

I am trying to create a greenDAO database session object for use in my junit tests. When i try to get the SQLiteDatabase object i always get null. No error is returned and i can't figure out why.

Below the code:

@RunWith(MockitoJUnitRunner.class)
public class ChatRoomModuleTest {

    SomeEntityDao someEntityDao;

    @Mock
    Context mMockContext;

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

    @Before
    public void Before(){

        DaoMaster.DevOpenHelper openHelper = new  DaoMaster.DevOpenHelper(mMockContext, "myapp-db", null);
        SQLiteDatabase db = openHelper.getWritableDatabase(); //always return null;
        DaoSession daoSession = new DaoMaster(db).newSession();
        someEntityDao = daoSession.getSomeEntityDao();

    }
}

Note: i know i can test it using android tests, but they are much more slow and unnecessary to test independent platform logic.

You mock the context. Shouldnt you set it up first before passing to DevOpneHelper? — Maciej Kowalski, May 06 '17 at 15:06
It cross my mind, but how to set it up properly? Don't know what the the helper expects. — MiguelSlv, May 06 '17 at 15:09
I can help properly setting up junit / mockito but what that class expects is out of my area of knowledge. — Maciej Kowalski, May 06 '17 at 15:13
I try to debug into the DevOpenHelper to see what it needs from context but, somehow, the debug doesn't go behind first stack call. The getWritableDatabase is not even debugable. — MiguelSlv, May 06 '17 at 15:24

score 0 · Accepted Answer · answered Jun 13 '17 at 16:54

Found the solution and involves several steps:

1) use Robolectric package to be able to create an Application

At app.gradle add:

//if your project use multidex
testCompile "org.robolectric:shadows-multidex:3.0"
//otherwise use
//testCompile 'org.robolectric:robolectric:3.1'

2) Build your test class like this:

@RunWith(RobolectricGradleTestRunner.class) //run test with roboteletric
@Config(constants = BuildConfig.class, sdk = 19)
public class test {

    MyEntityDao myEntityDao;
    DaoSession daoSession;

    @Before
    public void setUp() {

//use roboteletric to create a valid Application Object
        DaoMaster.DevOpenHelper openHelper = new DaoMaster.DevOpenHelper(RuntimeEnvironment.application, null, null);
        SQLiteDatabase db = openHelper.getWritableDatabase();
        Assert.assertNotNull(db);
        daoSession = new DaoMaster(db).newSession();
        myEntityDao = daoSession.getMyEntityDao();
    }


    @Test
    public void t1() {
        MyEntity myEntity = new MyEntity();
        myEntityDao.insert(MyEntity);
    }
}

3) Finally define working directory as posted here for your tests so Robolectric can find the project manifest file.

I am not sure if will work consistently on other tests at this time, and maybe would be preferable to use android tests instead. GreenDao doesn't seems tailored to be used outside the android.

Setting up greenDAO session object for a junit test

1 Answers1