Android unit testing fragment with roboletric in MPV application

I am reinventing my app using a classic MVP approach. In order to to this I read many many articles and tutorials, and what I came out with is that the best way is to :

• create an interface for the presenter and one for the view
• make fragments and activities implements view interfaces
• create an implementation of the presenter interface, which takes in the constructor an instance of the the view it manages, and hold a reference to the presenter inside the view's implementation.

So I have created this classes

VIEW INTERFACE

 public interface SignupEmailView extends BaseView {

        void fillEmail(String email);

        void onEmailInvalid(String error);

        void onDataValidated();
    }

PRESENTER INTERFACE

public interface SignupEmailPresenter {

    void initData(Bundle bundle);

    void validateData(String email);
}

VIEW IMPLEMENTATION

public class FrSignup_email extends BaseSignupFragmentMVP implements IBackHandler, SignupEmailView {

        public static String PARAM_EMAIL = "param_email";
        @Bind(R.id.signup_step2_new_scrollview)
        ScrollView mScrollview;
        @Bind(R.id.signup_step2_new_lblTitle)
        SuperLabel mLblTitle;
        @Bind(R.id.signup_step2_new_lblSubtitle)
        TextView mLblSubtitle;
        @Bind(R.id.signup_step2_new_txtEmail)
        EditText mTxtEmail;
        @Bind(R.id.signup_step2_new_btnNext)
        Button mBtnNext;
        protected SignupActivityView mActivity;
        SignupEmailPresenter mPresenter;

        public FrSignup_email() {
            // Required empty public constructor
        }

        public static FrSignup_email newInstance(String email) {
            FrSignup_email fragment = new FrSignup_email();
            Bundle b = new Bundle();
            b.putString(PARAM_EMAIL, email);
            fragment.setArguments(b);
            return fragment;
        }

@Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            mActivity = (SignupActivityView) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString()
                    + " must implement IResetPasswordBridge");
        }
    }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View view = loadView(inflater, container, savedInstanceState, R.layout.fragment_signup_email);
            mPresenter = new SignupEmailPresenterImpl(this);
            ButterKnife.bind(this, view);
            return view;
        }

        @Override
        public final void onViewCreated(View view, Bundle savedInstanceState) {
            super.onViewCreated(view, savedInstanceState);
            applyCircularReveal();

            mPresenter.initData(this.getArguments());

            mTxtEmail.setImeOptions(EditorInfo.IME_ACTION_NEXT);
            mTxtEmail.setOnEditorActionListener(new TextView.OnEditorActionListener() {
                @Override
                public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                    if (actionId == EditorInfo.IME_ACTION_NEXT) {
                        mPresenter.validateData(mTxtEmail.getText().toString());
                        return true;
                    }
                    return false;
                }
            });
            mTxtEmail.setOnTouchListener(new OnTouchCompoundDrawableListener_NEW(mTxtEmail, new OnTouchCompoundDrawableListener_NEW.OnTouchCompoundDrawable() {
                @Override
                public void onTouch() {
                    mTxtEmail.setText("");
                }
            }));
            mBtnNext.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    mPresenter.validateData(mTxtEmail.getText().toString());
                }
            });
        }

        @Override
        public void fillEmail(String email) {
            mTxtEmail.setText(email);
        }

        @Override
        public void onEmailInvalid(String error) {
            displayError(error);
        }

        @Override
        public void onDataValidated() {
            changeFieldToValid(mTxtEmail);
            setEmail(mTxtEmail.getText().toString());
            // the activity shows the next fragment
            mActivity.onEmailValidated();
        }

        @Override
        public boolean doBack() {
            if (!isLoading()) {
                mActivity.onEmailBack();
            }
            return true;
        }

        @Override
        public void displayError(String error) {
            changeFieldToInvalid(mTxtEmail);
            mLblSubtitle.setText(error);
            mLblSubtitle.setTextColor(ContextCompat.getColor(getActivity(), R.color.field_error));
        }
    }

PRESENTER IMPLEMENTATION

public class SignupEmailPresenterImpl implements SignupEmailPresenter {
    private SignupEmailView mView;

    public SignupEmailPresenterImpl(SignupEmailView view) {
        mView = view;
    }

    @Override
    public void initData(Bundle bundle) {
        if (bundle != null) {
            mView.fillEmail(bundle.getString(FrSignup_email.PARAM_EMAIL));
        }
    }

    @Override
    public void validateData(String password) {
        ValidationUtils_NEW.EmailStatus status = ValidationUtils_NEW.validateEmail(password);
        if (status != ValidationUtils_NEW.EmailStatus.VALID) {
            mView.onEmailInvalid(ValidationUtils_NEW.getEmailErrorMessage(status));
        } else {
            mView.onDataValidated();
        }
    }
}

Now the fragment is held by an activity which implements this view interface and has its own presenter

public interface SignupActivityView extends BaseView {

    void onEmailValidated();
    void onPhoneNumberValidated();
    void onPasswordValidated();
    void onUnlockCodeValidated();
    void onResendCodeClick();

    void onEmailBack();
    void onPhoneNumberBack();
    void onPasswordBack();
    void onConfirmCodeBack();

    void onSignupRequestSuccess(boolean resendingCode);
    void onSignupRequestFailed(String errorMessage);
    void onTokenCreationFailed();
    void onUnlockSuccess();
    void onUnlockError(String errorMessage);

    void showTermsAndConditions();
    void hideTermsAndConditions();
}

My idea is to have a unit test for each project unit, so for each view and presenter implementation I want a unit test, so I want to unit test my fragment with roboletric, and for example I want to test that if I click the "NEXT" button and the email is correct, the hosting Activity's onEmailValidated()method is called. This is my test class

public class SignupEmailViewTest {

    private SignupActivity_NEW mActivity;
    private SignupActivity_NEW mSpyActivity;
    private FrSignup_email mFragment;
    private FrSignup_email mSpyFragment;
    private Context mContext;

    @Before
    public void setUp() {
        final Context context = RuntimeEnvironment.application.getApplicationContext();
        this.mContext = context;

        mActivity = Robolectric.buildActivity(SignupActivity_NEW.class).create().visible().get();
        mSpyActivity = spy(mActivity);
        mFragment = FrSignup_email.newInstance("");
        mSpyFragment =spy(mFragment);
        mSpyActivity.getFragmentManager()
                .beginTransaction()
                .replace(R.id.signupNew_fragmentHolder, mSpyFragment)
                .commit();

        mSpyActivity.getFragmentManager().executePendingTransactions();
    }

    @Test
    public void testEmailValidation() {
        assertTrue(mSpyActivity.findViewById(R.id.signup_step2_new_lblTitle).isShown());
        assertTrue(mSpyActivity.findViewById(R.id.signup_step2_new_lblSubtitle).isShown());

        mSpyActivity.findViewById(R.id.signup_step2_new_btnNext).performClick();
        assertTrue(((SuperLabel) mSpyActivity.findViewById(R.id.signup_step2_new_lblSubtitle)).getText().equals(mContext.getString(R.string.email_empty)));

        ((EditText) mSpyActivity.findViewById(R.id.signup_step2_new_txtEmail)).setText("aaa@bbb.ccc");

        mSpyActivity.findViewById(R.id.signup_step2_new_btnNext).performClick();
        verify(mSpyFragment).onDataValidated();
        verify(mSpyActivity).onEmailValidated();
    }
}

everything works well, is just the last verify which doesn't work. Note that the previous verify works, so onEmailValidated is called for sure.

Aside from this specific case, I have some point to discuss: If with roboeletric I am forced to use an activity to instantiate a fragment, how can I test the fragment in complete isolation (which would be the unit tests goal)? I mean, if I use Robolectric.setupActivity(MyActivity.class) and the activity instantiates somewhere a fragment, it will load the activity and the fragment, which is good, but what if the activity manages a flow of fragments? How can I test the second or third fragment without manually navigating to it? Someone can say to use a dummy activity and use FragmentTestUtil.startFragment, but what in the fragment's onAttach() method is implemented the bridging with the parent activity? Is it me going on the wrong way or are this problems still unsolved?

thanks