This lesson focuses on understanding the use of the @DirtiesContext annotation in Spring Boot testing to manage test interactions and the application context.

Key Points:

1. Introduction to @DirtiesContext:
   • The @DirtiesContext annotation indicates that the Spring application context has been modified and should be closed and removed from the context cache.
   • In CashCardApplicationTests.java, there are two uses of this annotation:
     • At the class level (currently commented out).
     • At the method level on the shouldCreateANewCashCard test method (also commented out initially).
2. Commenting Out the Class-Level Annotation:

   • The class-level @DirtiesContext annotation is commented out to observe its effect:

     @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
     //@DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
     class CashCardApplicationTests {
     

   • Running all the tests after commenting out results in a test failure.

3. Analyzing the Test Failure:

   • The shouldReturnAllCashCardsWhenListIsRequested test fails with an AssertionFailedError, expecting 3 CashCards but finding 4.

     expected: 3
      but was: 4
     

   • The failure occurs because another test is interfering by creating a new Cash Card, which affects the shared application context.

4. Understanding @DirtiesContext:
   • @DirtiesContext helps by resetting the Spring application context to a clean state after each test, preventing side effects between tests.
   • When removed at the class level, the tests share the same application context, leading to interference.
5. Best Practices with @DirtiesContext:
   • While @DirtiesContext can prevent test interference, it should not be used indiscriminately due to the overhead of reloading the application context.
   • It's better to apply it selectively to specific test methods that modify the context in a way that could affect other tests.
6. Applying @DirtiesContext at Method Level:

   • Leave the class-level @DirtiesContext commented out.

   • Uncomment and apply @DirtiesContext on the specific test method that creates a new Cash Card:

     //@DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
     class CashCardApplicationTests {
         ...
     
         @Test
         @DirtiesContext
         void shouldCreateANewCashCard() {
             ...
         }
     

   • This ensures that only the application context for this test is reset after execution.

7. Rerunning the Tests:
   • After making these changes, running the tests again shows that all tests pass successfully.

Conclusion:

• Proper use of @DirtiesContext ensures test isolation without unnecessary performance costs.
• Applying it at the method level prevents inter-test interference by resetting the application context only when needed.

테스트 상호 작용과 @DirtiesContext

이번 강의는 Spring Boot 테스트에서 @DirtiesContext 애노테이션을 이해하고, 테스트 간의 상호 작용과 애플리케이션 컨텍스트를 관리하는 방법에 대해 다룹니다.

주요 내용:

1. @DirtiesContext 소개:
   • @DirtiesContext 애노테이션은 Spring 애플리케이션 컨텍스트가 변경되었음을 나타내며, 컨텍스트를 닫고 컨텍스트 캐시에서 제거하도록 합니다.
   • CashCardApplicationTests.java에서 이 애노테이션은 두 군데 사용됩니다:
     • 클래스 레벨(현재 주석 처리됨).
     • shouldCreateANewCashCard 테스트 메소드 레벨(초기에 주석 처리됨).
2. 클래스 레벨 애노테이션 주석 처리:

   • 클래스 레벨의 @DirtiesContext 애노테이션을 주석 처리하여 영향도를 관찰합니다:

     @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
     //@DirtiesContext(classMode = ClassMode.AFTER_EACH_TEST_METHOD)
     class CashCardApplicationTests {
     

   • 주석 처리 후 모든 테스트를 실행하면 테스트 실패가 발생합니다.

3. 테스트 실패 분석:

   • shouldReturnAllCashCardsWhenListIsRequested 테스트가 AssertionFailedError와 함께 실패하며, 기대했던 CashCard 수는 3개였지만 실제로는 4개였습니다.

     expected: 3
      but was: 4
     

   • 이는 다른 테스트에서 새로운 Cash Card를 생성하여 공유된 애플리케이션 컨텍스트에 영향을 미쳤기 때문입니다.

4. @DirtiesContext 이해하기:
   • @DirtiesContext는 각 테스트 후에 Spring 애플리케이션 컨텍스트를 초기 상태로 재설정하여 테스트 간의 부작용을 방지합니다.
   • 클래스 레벨에서 제거하면 테스트들이 동일한 애플리케이션 컨텍스트를 공유하게 되어 상호 간섭이 발생합니다.