package code.test.mockito;

/**
 * @author max
 * @date 2020/7/13
 * @time 16:28
 */
public class User {
    private String userName;
    private String email;
    private String passwordMd5CheckSum;

    public User() {
    }

    public User(String userName, String email, String passwordMd5CheckSum) {
        this.userName = userName;
        this.email = email;
        this.passwordMd5CheckSum = passwordMd5CheckSum;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public String getPasswordMd5CheckSum() {
        return passwordMd5CheckSum;
    }

    public void setPasswordMd5CheckSum(String passwordMd5CheckSum) {
        this.passwordMd5CheckSum = passwordMd5CheckSum;
    }
}

package code.test.mockito;

import org.apache.commons.codec.digest.DigestUtils;

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

/**
 * @author max
 * @date 2020/7/13
 * @time 16:27
 */
public class LoginService {

    private static List<User> existingUsers = new ArrayList<>();

    static {
        existingUsers.add(new User("max", "max@mocki.to",
                "5f4dcc3b5aa765d61d8327deb882cf99"));
    }

    public User login(String userName, String password) {
        for (User user : LoginService.existingUsers) {
            if (user.getUserName().equals(userName) &&
                    DigestUtils.md5Hex(password).endsWith(user.getPasswordMd5CheckSum())) {
                return user;
            }
        }
        return null;
    }
}

package code.test.mockito;

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

/**
 * @author max
 * @date 2020/7/13
 * @time 15:46
 */
public class MockitoTest {

    @Mock()
    private LoginService loginService;

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

    @Test
    public void testLoginOne() {
        // Create a stubbing and verify the expected behavior.
        String mockedUserName = "max";
        String mockedPassword = "???";
        String mockedEmail = "mocked@mocki.to";
        String mockedPasswordMd5Checksum = "This is a mocked user...";
        Mockito.when(this.loginService.login(mockedUserName, mockedPassword)).thenReturn(
                new User(mockedUserName, mockedEmail, mockedPasswordMd5Checksum));
        User user = this.loginService.login(mockedUserName, mockedPassword);
        Assert.assertEquals(user.getUserName(), mockedUserName);
        Assert.assertEquals(user.getEmail(), mockedEmail);
        Assert.assertEquals(user.getPasswordMd5CheckSum(), mockedPasswordMd5Checksum);
    }

    @Test
    public void testLoginTwo() {
        User user = this.loginService.login("max", "password");
        // The mocked "loginService" instance returns null by default(when there's no stubbing).
        Assert.assertNull(user);
    }

    @Test
    public void testLoginThree() {
        LoginService localLoginService = new LoginService();
        User user = localLoginService.login("max", "password");
        // A non-mocked "loginService" instance can still work as before, which means
        // the "@Mock" annotation only affects the class instance, not the class.
        Assert.assertNotNull(user);
    }
}