Testing APIs with JUnit and Mockito

When developing APIs in Spring Boot, it is essential to thoroughly test the functionality of the API to ensure that it behaves as expected and handles various scenarios correctly. JUnit and Mockito are popular frameworks for writing unit tests in Java.

JUnit is a testing framework that provides annotations and assert methods to write and run tests. It allows you to define test methods, set up test data, and assert expected outcomes. Mockito, on the other hand, is a mocking framework that allows you to create mock objects of dependencies for unit testing.

Let's take a look at an example of how to write a unit test for an API using JUnit and Mockito:

1// Mock service
2MyService myService = Mockito.mock(MyService.class);
3
4// Set up mock response
5Mockito.when(myService.getData()).thenReturn("Test Data");
6
7// Create instance of controller
8MyController myController = new MyController(myService);
9
10// Perform test
11String result = myController.getData();
12
13// Verify the result
14Assert.assertEquals("Test Data", result);

xxxxxxxxxx

class Main {

  public static void main(String[] args) {

    // Mock service

    MyService myService = Mockito.mock(MyService.class);

​

    // Set up mock response

    Mockito.when(myService.getData()).thenReturn("Test Data");

​

    // Create instance of controller

    MyController myController = new MyController(myService);

​

    // Perform test

    String result = myController.getData();

​

    // Verify the result

    Assert.assertEquals("Test Data", result);

  }

}