AllCountriesViewModelUnitTest.java

package com.patloew.countries;

import android.support.v7.widget.RecyclerView;

import com.patloew.countries.data.local.CountryRepo;
import com.patloew.countries.data.model.Country;
import com.patloew.countries.data.remote.CountryApi;
import com.patloew.countries.ui.main.recyclerview.CountryAdapter;
import com.patloew.countries.ui.main.viewpager.CountriesView;
import com.patloew.countries.ui.main.viewpager.all.AllCountriesViewModel;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareOnlyThisForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import java.util.ArrayList;
import java.util.List;

import io.reactivex.Observable;
import io.reactivex.Single;

import static org.mockito.Mockito.doReturn;
import static org.mockito.Mockito.times;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.verifyZeroInteractions;

/* Copyright 2016 Patrick Löwenstein
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License. */

@RunWith(PowerMockRunner.class)
@PrepareOnlyThisForTest({ RecyclerView.Adapter.class })
public class AllCountriesViewModelUnitTest {

    @Rule RxSchedulersOverrideRule rxSchedulersOverrideRule = new RxSchedulersOverrideRule();

    @Mock CountryApi countryApi;
    CountryAdapter adapter;
    @Mock CountryRepo countryRepo;

    @Mock CountriesView countriesView;
    AllCountriesViewModel allCountriesViewModel;

    @Before
    public void setup() {
        MockitoAnnotations.initMocks(this);

        adapter = PowerMockito.mock(CountryAdapter.class);
        PowerMockito.doAnswer(invocation -> null).when((RecyclerView.Adapter)adapter).notifyDataSetChanged();

        doReturn(Observable.never()).when(countryRepo).getFavoriteChangeObservable();

        allCountriesViewModel = new AllCountriesViewModel(adapter, countryApi, countryRepo);
        allCountriesViewModel.attachView(countriesView, null);
    }

    @Test
    public void onRefresh_success() {
        List<Country> countryList = new ArrayList<>();
        countryList.add(new Country());

        doReturn(Single.just(countryList)).when(countryApi).getAllCountries();

        allCountriesViewModel.reloadData();

        verify(adapter, times(1)).setCountryList(countryList);
        verify(adapter, times(1)).notifyDataSetChanged();
        verify(countriesView, times(1)).onRefresh(true);
    }

    @Test
    public void onRefresh_error() {
        doReturn(Single.error(new RuntimeException("Error getting countries"))).when(countryApi).getAllCountries();

        allCountriesViewModel.reloadData();

        verifyZeroInteractions(adapter);
        verify(countriesView, times(1)).onRefresh(false);
    }
}