🎓 Top 15 Udemy Courses (80-90% Discount): My Udemy Courses - Ramesh Fadatare — All my Udemy courses are real-time and project oriented courses.
▶️ Subscribe to My YouTube Channel (178K+ subscribers): Java Guides on YouTube
▶️ For AI, ChatGPT, Web, Tech, and Generative AI, subscribe to another channel: Ramesh Fadatare on YouTube
1. Introduction
When writing tests in Mockito, we often use annotations like @Mock, @InjectMocks, @Spy, and @Captor to simplify the mock creation process. But for these annotations to be effective, they must be initialized. One of the ways to automatically initialize these annotations is by using the @RunWith(MockitoJUnitRunner.class) annotation. This ensures that all the Mockito annotations are initialized, which means we don't have to manually call MockitoAnnotations.initMocks(this).
2. Example Steps
1. Define an interface and its implementation.
2. Define a service class that uses the interface.
3. Create a test class.
4. Within the test class, annotate it with @RunWith(MockitoJUnitRunner.class).
5. Use Mockito annotations like @Mock and @InjectMocks within the test class.
6. Write the test methods.
7. Run the tests.
3. Mockito @RunWith Example
import org.junit.Test;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.runners.MockitoJUnitRunner;
interface Calculator {
int add(int a, int b);
}
class SimpleCalculator implements Calculator {
@Override
public int add(int a, int b) {
return a + b;
}
}
@RunWith(MockitoJUnitRunner.class)
public class CalculatorTest {
@Mock
Calculator mockCalculator;
@InjectMocks
SimpleCalculator simpleCalculator;
@Test
public void testAddition() {
// Mock the add method of mockCalculator
when(mockCalculator.add(10, 20)).thenReturn(30);
// Call the add method
int result = simpleCalculator.add(10, 20);
// Assert the result
assertEquals(30, result);
}
}
Output:
The test will pass, ensuring that the mocked add method of the Calculator interface is used within the SimpleCalculator implementation.
4. Step By Step Explanation
1. We define an interface Calculator and a simple implementation of SimpleCalculator.
2. We then have a CalculatorTest class annotated with @RunWith(MockitoJUnitRunner.class). This ensures that all Mockito annotations inside this class are initialized without the need to explicitly call MockitoAnnotations.initMocks(this).
3. Inside the test class, we declare a mock for the Calculator interface using the @Mock annotation.
4. We also use the @InjectMocks annotation for the SimpleCalculator, which will use the mocked Calculator.
5. In the testAddition method, we mock the add method of mockCalculator to always return 30 when called with 10 and 20.
6. We then call the add method of our simpleCalculator and assert the result.
7. Thanks to the @RunWith(MockitoJUnitRunner.class) annotation, the initialization of the mock and the injection into simpleCalculator happen automatically, making our test setup cleaner and more efficient.
Related Mockito Annotations
Mockito @InjectMocks Annotation Tutorial
Mockito @Spy Annotation Tutorial
Mockito @Captor Annotation Tutorial
Mockito @RunWith Example
Mockito @ExtendWith Example
My Top and Bestseller Udemy Courses. The sale is going on with a 70 - 80% discount. The discount coupon has been added to each course below:
Build REST APIs with Spring Boot 4, Spring Security 7, and JWT
![[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25](https://img-c.udemycdn.com/course/750x422/6852721_b512_2.jpg "[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25")
[NEW] Learn Apache Maven with IntelliJ IDEA and Java 25
ChatGPT + Generative AI + Prompt Engineering for Beginners
Spring 7 and Spring Boot 4 for Beginners (Includes 8 Projects)
Available in Udemy for Business
Building Real-Time REST APIs with Spring Boot - Blog App
Available in Udemy for Business
Building Microservices with Spring Boot and Spring Cloud
Available in Udemy for Business
Java Full-Stack Developer Course with Spring Boot and React JS
Available in Udemy for Business
Build 5 Spring Boot Projects with Java: Line-by-Line Coding
Testing Spring Boot Application with JUnit and Mockito
Available in Udemy for Business
Spring Boot Thymeleaf Real-Time Web Application - Blog App
Available in Udemy for Business
Master Spring Data JPA with Hibernate
Available in Udemy for Business
Spring Boot + Apache Kafka Course - The Practical Guide
Available in Udemy for Business
Comments
Post a Comment
Leave Comment