如何使用 Mockito 模拟 PreparedStatement

Question

I have the following function which changes the username of a user in a MySQL database:

public User changeUsername (ChangeUsername ChangeUsername) {
    // Getting user from database
    String sql = "select * from users where username='" + ChangeUsername.getUsername() + "'";
    List<User> users = jdbcTemplate.query(sql, new UserMapper());
    User user = users.get(0);
    // Getting encoded password from database
    String encodedPassword = user.getPassword();
    // Getting password input from user
    String rawPassword = ChangeUsername.getPassword();
    // Comparing passwords
    boolean isPasswordMatch = passwordEncoder.matches(rawPassword, encodedPassword);
    // If password matches
    if(isPasswordMatch){
        // Getting current userrname
        String username = ChangeUsername.getUsername();
        // Getting new username
        String newusername = ChangeUsername.getNewusername();
        // Updating username in database with prepared statement
        String update = "update users set username = ? where username = ?";
        Connection conn;
        try {
            conn = datasource.getConnection();
            PreparedStatement preparedStatement = conn.prepareStatement(update);
            preparedStatement.setString(1, newusername );
            preparedStatement.setString(2, username);
            preparedStatement.executeUpdate();
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return user;
    }
    return null;
   }

I am trying to test the function using Mockito and JUnit 5 however I am getting an assertion error when calling assertEquals to check if the username is being changed successfully in the test code. Therefore the username is not being changed correctly when testing the function. Below is my test code:

@RunWith(MockitoJUnitRunner.class)
public class ChangeUsernameTest {

    UserDaoImpl userdaoimpl = mock(UserDaoImpl.class);
    UserDao userdao = mock(UserDao.class);
    @Mock
    JdbcTemplate jdbcTemplate;
    @Mock
    private PreparedStatement stmt;
    @Mock
    private Connection c;
    @Mock
    private DataSource ds;
    @Mock
    ChangeUsername changeusername;
    @Mock
    User user;
    @BeforeEach
    public void setUp() {
      MockitoAnnotations.initMocks(this);
      user = new User();
      changeusername = new ChangeUsername();
      try {
            when(c.prepareStatement(any(String.class))).thenReturn(stmt);
            when(ds.getConnection()).thenReturn(c);
            doNothing().when(stmt).setString(any(int.class), any(String.class));
            when(stmt.execute()).thenReturn(Boolean.TRUE);
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
    @Test
    public void setUserDetails() {
        user.setAddress("A");
        user.setEmail("B");
        user.setFirstname("C");
        user.setLastname("D");
        user.setPassword("E");
        user.setUsername("F");
    }
    @Test
    public void testSetUsername() {
        changeusername.setUsername("F");
        assertEquals(changeusername.getUsername(), "F");
    }
    @Test
    public void testSetPassword() {
        changeusername.setUsername("E");
        assertEquals(changeusername.getUsername(), "E");
    }
    @Test
    public void testSetNewUsername() {
        changeusername.setNewusername("X");
        assertEquals(changeusername.getNewusername(), "X");
    }
    @Test
    public void testChangeUsername() {
        int update = jdbcTemplate.update(any(String.class), any(Object.class));
        when(userdaoimpl.register(user)).thenReturn(update);
        userdaoimpl.register(user);
        when(userdaoimpl.changeUsername(changeusername)).thenReturn(user);
        userdaoimpl.changeUsername(changeusername);
        assertEquals("X", user.getUsername());
    }
}

Answer 1

//USE PowerMockito it is easy as shown below




@RunWith(PowerMockRunner.class)
@PrepareForTest({yourtarget.class,datasource.class})
public class DBTest {


    @Mock
    private Connection con;

    @Mock
    private PreparedStatement stmt;

    @Mock
    private ResultSet rs;


    @Before
    public void setUpBeforeClass() throws Exception {
        MockitoAnnotations.initMocks(this);

    }

    @Test
    public void testMethod() throws SQLException {
        PowerMockito.mockStatic( DataSource.class );
        try {
            when( DataSource.getConnection() ).thenReturn( con );
        } catch (Exception e) {
            e.printStackTrace();
        }
        when( con.prepareStatement( any()) ).thenReturn( stmt );
        when( stmt.executeUpdate() ).thenReturn( 1 );

    }

}