Testing – Techglot

Index

Junit
Mockito
testing private method (reflection ,powermock)

2 testing fameworks- MOckito abd Sping testing

	MOck	MOckBean
annotation	pary of Mockitoframework	SPring testing framework
framework	@RunWith(MockitoJUnitRunner.class) public class MyServiceTest { @Mock private MyRepository myRepository;	@SpringBootTest public class MyServiceIntegrationTest { @Autowired private MyService myService; @MockBean private MyRepository myRepository;
Purpose	UnitTetsing	Integration testing

Spy vs Mock

	@spy	@Mock
Functionality	A partially mocked version of a real object.	A complete replacement for a real object.
Creation	Wraps an existing object	Creates a new object
Control	Partial control (can define specific behaviors for specific methods)	Full control over behavior
Use case	Testing interactions within a real object with some real behavior	Isolating dependencies, unit testing with specific behavior
access	can access private methods of the original object	cannot access private methods of the original object
example	below code	below code //

Mock usage

// Interface we want to test
public interface EmailService {
  void sendEmail(String recipient, String message);
}

// Test class using mock
@Test
public void testSendEmail() {
  // Create a mock object of EmailService
  EmailService mockEmailService = Mockito.mock(EmailService.class);

  // Define behavior for the mock object
  Mockito.when(mockEmailService.sendEmail("user@example.com", "Hello world!")).thenReturn(true);

  // Use the mock object in your test logic
  myService.sendNotification(mockEmailService, "user@example.com", "Hello world!");

  // Verify interactions with the mock object
  Mockito.verify(mockEmailService).sendEmail("user@example.com", "Hello world!");
}

IN above example :

We create a mock object of EmailService using Mockito.mock.
We define behavior for the sendEmail method using Mockito.when. Here, it always returns true.
We use the mock object in the test and verify its interaction later.

Spy usage

// Real implementation of EmailService
public class RealEmailService implements EmailService {
  @Override
  public void sendEmail(String recipient, String message) {
    // Send email logic goes here (not shown for simplicity)
  }
}

// Test class using spy
@Test
public void testSendEmailWithSpy() {
  // Create a real object
  EmailService realEmailService = new RealEmailService();

  // Create a spy object from the real object
  EmailService spyEmailService = Mockito.spy(realEmailService);

  // Define behavior for specific method (optional)
  Mockito.when(spyEmailService.sendEmail("admin@example.com", "Alert!")).thenReturn("Sent successfully");

  // Use the spy object in your test logic
  myService.sendNotification(spyEmailService, "user@example.com", "Hello world!");
  myService.sendNotification(spyEmailService, "admin@example.com", "Alert!");

  // Verify interactions (optional)
  Mockito.verify(spyEmailService, times(2)).sendEmail(anyString(), anyString());
}

IN above example :

Create a real RealEmailService object.
Create a spy of the RealEmailService using Mockito.spy.
Define behavior for the sendEmail method to return a specific message for “admin@example.com” email.
Use the spy object and verify interactions (optional).

		<dependency>
			<groupId>org.powermock</groupId>
			<artifactId>powermock-module-junit4</artifactId>
			<version>1.7.4</version>
		</dependency>

https://www.learnbestcoding.com/post/21/unit-test-private-methods-and-classes

REfernce

https://www.tutorialspoint.com/mockito/mockito_spying.htm

Category: Testing

Junit and Mocking and spy