Using ChatGPT to Refine Java Unit Tests – Episode 23

Initial coverage

JaCoCo run after debugging shows overall product coverage 87.3 %. ValidateUser.java 100 %, User.java 34.1 %, PasswordRecovery.java 50.5 %.

Step 1 – Adjust SendSms.java

Comment out debug statements.

Replace catch blocks with a simplified version that logs the error via logger.error(e.getMessage()) and returns false.

Step 2 – Regenerate UserTest.java

Prompt to ChatGPT: “Generate unit‑test cases for the code below.” Resulting JUnit 5 test class includes:

package ebusiness;
import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

public class UserTest {
    private User user;
    @BeforeEach
    public void setUp() {
        user = new User("testUser", "password123");
    }
    @Test public void testUsernameValid() { assertEquals("testUser", user.getUsername()); }
    @Test public void testPasswordValid() { assertEquals("password123", user.getPassword()); }
    @Test public void testPhoneDefault() { assertEquals("13611223344", user.getPhone()); }
    @Test public void testEmailDefault() { assertEquals("[email protected]", user.getEmail()); }
    @Test public void testSetUsernameValid() { user.setUsername("newUser"); assertEquals("newUser", user.getUsername()); }
    @Test public void testSetUsernameInvalid() {
        Exception e = assertThrows(IllegalArgumentException.class, () -> user.setUsername(""));
        assertEquals("无效的用户账号", e.getMessage());
        assertThrows(IllegalArgumentException.class, () -> user.setUsername("abc"));
        assertThrows(IllegalArgumentException.class, () -> user.setUsername(null));
    }
    // Additional tests for password, phone, email setters and constructors omitted for brevity
}

Uses @BeforeEach to create a fresh User instance for each test, includes normal‑case and exception‑case assertions, and replaces plain assertXXX calls with Assertions.assertXXX. The test suite runs successfully.

Step 3 – Adjust PasswordRecoveryTest.java

Add Maven dependency powermock-reflect version 2.0.9 to pom.xml:

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-reflect</artifactId>
  <version>2.0.9</version>
  <scope>test</scope>
</dependency>

Test class employs JUnit 5, Mockito, PowerMock, and Whitebox to mock static utilities and external services:

package ebusiness;
import static org.mockito.ArgumentMatchers.*;
import static org.mockito.Mockito.*;
import org.junit.jupiter.api.*;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.*;
import org.mockito.junit.jupiter.MockitoExtension;
import org.powermock.reflect.Whitebox;
import demo.SendSms;

@ExtendWith(MockitoExtension.class)
class PasswordRecoveryTest {
    @Mock private Util mockUtil;
    @Mock private SendSms mockSendSms;
    @InjectMocks private PasswordRecovery passwordRecovery;
    @Mock private UserRepository userRepository;

    @BeforeEach void setUp() throws SQLException {
        passwordRecovery = new PasswordRecovery();
        Whitebox.setInternalState(passwordRecovery, "util", mockUtil);
    }

    @Test void testSendVerificationCode_InvalidContact() throws Exception {
        String result = passwordRecovery.sendVerificationCode("invalid_contact");
        Assertions.assertEquals("您输入的手机号或Email格式不正确！", result);
    }

    @Test void testRecoverPassword_Success() throws SQLException {
        // arrange mocks for verifyCode, getPassword, storeOldPassword, updatePassword, verifyPassword
        String result = passwordRecovery.recoverPassword("123456", newHashed, userRepository, 123);
        Assertions.assertEquals("0", result);
    }
    // Additional tests for password‑used, old‑password error, SQLException, contact‑type detection, SMS/Email success, etc.
}

Coverage improvement

SendSms.java: 65.2 % → 88.7 %

User.java: 34.1 % → 97.6 %

PasswordRecovery.java: 50.5 % → 79.7 %

Overall product code: 73.7 % → 81.5 %

Unit‑test count analysis

Table 4‑2 (referenced image) lists the number of unit tests per class and the percentage of code exercised.