Login MVP

AuthenticationManager.java

package com.doordash.mvpexample.data;

import android.support.annotation.NonNull;
import android.support.annotation.VisibleForTesting;

import com.doordash.mvpexample.api.AuthenticationApi;
import com.doordash.mvpexample.helpers.SharedPreferencesHelper;
import com.doordash.mvpexample.models.Token;

import javax.inject.Inject;

import io.reactivex.Single;

public class AuthenticationManager {
    @VisibleForTesting
    static final String AUTH_TOKEN_SHARED_PREFS_KEY = "auth-token";

    private SharedPreferencesHelper sharedPreferencesHelper;
    private AuthenticationApi authenticationApi;

    @Inject
    public AuthenticationManager(AuthenticationApi authenticationApi,
                                 SharedPreferencesHelper sharedPreferencesHelper) {
        this.sharedPreferencesHelper = sharedPreferencesHelper;
        this.authenticationApi = authenticationApi;
    }

    public Single<Token> getAuthToken(@NonNull String email, @NonNull String password) {
        return Single.fromCallable(() -> {
            String sharedPreferencesString = sharedPreferencesHelper.getString(AUTH_TOKEN_SHARED_PREFS_KEY);
            if (sharedPreferencesString != null) {
                return Single.just(new Token(sharedPreferencesString));
            }
            return authenticationApi.getTokenForCredentials(email, password).map(token -> {
                sharedPreferencesHelper.save(AUTH_TOKEN_SHARED_PREFS_KEY, token.getToken());
                return token;
            });
        }).flatMap(tokenSingle -> tokenSingle);
    }
}

AuthenticationManagerTest.java

package com.doordash.mvpexample.data;

import com.doordash.mvpexample.api.AuthenticationApi;
import com.doordash.mvpexample.helpers.SharedPreferencesHelper;
import com.doordash.mvpexample.models.Token;

import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;

import io.reactivex.Single;

import static com.doordash.mvpexample.data.AuthenticationManager.AUTH_TOKEN_SHARED_PREFS_KEY;
import static junit.framework.Assert.assertEquals;
import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;


public class AuthenticationManagerTest {
    private static final String EMAIL = "user@website.com";
    private static final String PASSWORD = "password";
    private static final String API_TOKEN = "api-token";
    private static final String CACHED_TOKEN = "cached-token";

    @Mock
    AuthenticationApi authenticationApi;
    @Mock
    SharedPreferencesHelper sharedPreferencesHelper;
    private AuthenticationManager authenticationManager;

    @Before
    public void setUp() throws Exception {
        // instantiate manager with mock dependencies
        MockitoAnnotations.initMocks(this);
        authenticationManager = new AuthenticationManager(authenticationApi, sharedPreferencesHelper);
    }

    @Test
    public void getAuthToken_whenNotCached_callApiAndCache() throws Exception {
        when(sharedPreferencesHelper.getString(AUTH_TOKEN_SHARED_PREFS_KEY))
                .thenReturn(null); // cache is empty
        when(authenticationApi.getTokenForCredentials(EMAIL, PASSWORD))
                .thenReturn(Single.just(new Token(API_TOKEN))); // api will succeed
        Token token = authenticationManager.getAuthToken(EMAIL, PASSWORD).blockingGet();
        assertEquals(API_TOKEN, token.getToken());
        verify(sharedPreferencesHelper).save(AUTH_TOKEN_SHARED_PREFS_KEY, API_TOKEN);
    }

    @Test
    public void getAuthToken_whenCached_getCachedValue() throws Exception {
        when(sharedPreferencesHelper.getString(AUTH_TOKEN_SHARED_PREFS_KEY))
                .thenReturn(CACHED_TOKEN); // cache is filled
        Token token = authenticationManager.getAuthToken(EMAIL, PASSWORD).blockingGet();
        assertEquals(CACHED_TOKEN, token.getToken());
    }
}

LoginActivity.java

package com.doordash.mvpexample.ui.login;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.AppCompatEditText;
import android.widget.Toast;

import com.doordash.mvpexample.R;
import com.doordash.mvpexample.application.MvpApplication;
import com.doordash.mvpexample.ui.MainActivity;

import javax.inject.Inject;

import butterknife.BindView;
import butterknife.ButterKnife;
import butterknife.OnClick;

public class LoginActivity extends AppCompatActivity implements LoginContract.View {

    @Inject
    LoginContract.Presenter presenter;
    @BindView(R.id.login_email)
    AppCompatEditText emailEditText;
    @BindView(R.id.login_password)
    AppCompatEditText passwordEditText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);
        MvpApplication.getAppComponent().inject(this);
        ButterKnife.bind(this);
        presenter.setView(this);
    }

    @Override
    protected void onPause() {
        presenter.onPause();
        super.onPause();
    }

    @NonNull
    @Override
    public String getEmailInput() {
        return emailEditText.getText().toString();
    }

    @NonNull
    @Override
    public String getPasswordInput() {
        return passwordEditText.getText().toString();
    }

    @Override
    public void goToMainActivity() {
        startActivity(MainActivity.makeIntent(this));
    }

    @Override
    public void showError(@NonNull String error) {
        Toast.makeText(this, error, Toast.LENGTH_LONG).show();
    }

    @OnClick(R.id.login_button)
    public void onClickLoginButton() {
        presenter.onClickLoginButton();
    }
}

LoginContract.java

package com.doordash.mvpexample.ui.login;

import android.support.annotation.NonNull;

import com.doordash.mvpexample.ui.BaseContract;

public class LoginContract {

    public interface View {
        void goToMainActivity();

        void showError(@NonNull String error);

        @NonNull
        String getEmailInput();

        @NonNull
        String getPasswordInput();
    }

    public interface Presenter {
        /**
         * Late initializer for {@link View} interface
         */
        void setView(View view);

        void onPause();

        void onClickLoginButton();
    }
}

LoginPresenter.java

package com.doordash.mvpexample.ui.login;


import com.doordash.mvpexample.data.AuthenticationDataSource;
import com.doordash.mvpexample.helpers.rx.RxSchedulerProvider;
import com.doordash.mvpexample.models.Token;
import com.doordash.mvpexample.ui.BaseRxPresenter;

import io.reactivex.SingleObserver;
import io.reactivex.disposables.Disposable;

public class LoginPresenter implements LoginContract.Presenter {

    private AuthenticationManager authenticationManager;

    public LoginPresenter(RxSchedulerProvider rxSchedulerProvider,
                          AuthenticationManager authenticationManager) {
        super(rxSchedulerProvider);
        this.authenticationManager = authenticationManager;
    }

    public void onClickLoginButton() {
        authenticationManager.getAuthToken(view.getEmailInput(), view.getPasswordInput())
                .subscribe(new SingleObserver<Token>() {
                    @Override
                    public void onSubscribe(@io.reactivex.annotations.NonNull Disposable d) {
                        addDisposable(d);
                    }

                    @Override
                    public void onSuccess(@io.reactivex.annotations.NonNull Token token) {
                        view.goToMainActivity();
                    }

                    @Override
                    public void onError(@io.reactivex.annotations.NonNull Throwable e) {
                        view.showError(e.getLocalizedMessage());
                    }
                });
    }
}

LoginPresenterTest.java

package com.doordash.mvpexample.ui.login;

import com.doordash.mvpexample.data.AuthenticationDataSource;
import com.doordash.mvpexample.helpers.rx.ImmediateRxSchedulerProvider;
import com.doordash.mvpexample.models.Token;

import org.junit.Before;
import org.junit.Test;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;

import io.reactivex.Single;

import static org.mockito.Mockito.verify;
import static org.mockito.Mockito.when;

public class LoginPresenterTest {
    private static final String EMAIL = "user@website.com";
    private static final String PASSWORD = "password";
    private static final String TOKEN = "token";
    @Mock
    AuthenticationDataSource authenticationDataSource;
    @Mock
    LoginContract.View loginView;
    LoginPresenter presenter;

    @Before
    public void setUp() throws Exception {
        // instantiate presenter with mock dependencies
        // pass in ImmediateRxSchedulerProvider to make rx calls blocking
        MockitoAnnotations.initMocks(this);
        presenter = new LoginPresenter(new ImmediateRxSchedulerProvider(), authenticationDataSource);
        presenter.setView(loginView);
        // mock view getters
        when(loginView.getEmailInput()).thenReturn(EMAIL);
        when(loginView.getPasswordInput()).thenReturn(PASSWORD);
    }

    @Test
    public void onClickLoginButton_whenLoginSucceeds_goToMainActivity() throws Exception {
        when(authenticationDataSource.getAuthToken(EMAIL, PASSWORD))
                .thenReturn(Single.just(new Token(TOKEN))); // fake successful login
        presenter.onClickLoginButton();
        verify(loginView).goToMainActivity();
    }

    @Test
    public void onClickLoginButton_whenLoginFails_showError() throws Exception {
        Exception error = new Exception("error message");
        when(authenticationDataSource.getAuthToken(EMAIL, PASSWORD))
                .thenReturn(Single.error(error)); // fake failed login
        presenter.onClickLoginButton();
        verify(loginView).showError(error.getLocalizedMessage());
    }
}

Token.java

package com.doordash.mvpexample.models;

import android.support.annotation.NonNull;

public class Token {

    private String token;

    public Token(@NonNull String token) {

        this.token = token;
    }

    public String getToken() {
        return token;
    }
}