@Test
public void isUserSignedInReturnsTrue() {

    AccessToken accessToken = TestDataFactory.makeAccessToken();
    stubPreferencesHelperGetAccessToken(accessToken);
    TestSubscriber<Boolean> testSubscriber = new TestSubscriber<>();
    mDataManager.isUserSignedIn().subscribe(testSubscriber);
    testSubscriber.assertCompleted();
    testSubscriber.assertValue(true);
}