Spring Boot Testing Spring Applications Questions and Answers

Question 1

A developer needs to write a test for a Spring MVC `@RestController` that focuses exclusively on the web layer.
The test should verify request mappings, JSON serialization/deserialization, and exception handling without loading the service or repository layers.
Which annotation is most suitable for this purpose?

Accepted Answer

`@WebMvcTest(MyController.class)`

Answer

`@SpringBootTest`

Answer

`@DataJpaTest`

Answer

`@ExtendWith(MockitoExtension.class)`

Question 2

In a Spring Boot integration test annotated with `@SpringBootTest`, what is the primary function of the `@MockBean` annotation?

Accepted Answer

To add a new bean or replace an existing bean in the `ApplicationContext` with a Mockito mock.

Answer

To create a mock object that is not part of the Spring `ApplicationContext`.

Answer

To inject a real bean from the `ApplicationContext` into the test class.

Answer

To configure a specific test profile for the `ApplicationContext`.

Question 3

When writing a test class annotated with `@DataJpaTest`, which of the following behaviors is NOT part of its default configuration?

Accepted Answer

Loading the full application context, including web controllers and services.

Answer

Configuring an in-memory embedded database (like H2).

Answer

Scanning for `@Entity` classes and Spring Data repositories.

Answer

Executing each test method within a transaction that is rolled back by default.

Question 4

A developer needs to write a full integration test for a REST API. The test must start the application on an actual (but random) port and make real HTTP requests to the endpoints to verify the complete request-response cycle. Which annotation and helper class combination is best suited for this scenario?

Accepted Answer

`@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)` and `TestRestTemplate`

Answer

`@WebMvcTest` and `MockMvc`

Answer

`@SpringBootTest(webEnvironment = WebEnvironment.MOCK)` and `MockMvc`

Answer

`@DataJpaTest` and `TestEntityManager`

Question 5

An integration test requires a database connection whose JDBC URL is determined at runtime by a Testcontainers-managed Docker container. Which annotation should be used on a static method within the test class to add this dynamically generated URL to the Spring `Environment` before the context is refreshed?

Accepted Answer

`@DynamicPropertySource`

Answer

`@TestPropertySource(properties = "spring.datasource.url=...")`

Answer

`@ContextConfiguration`

Answer

`@ActiveProfiles("test-container")`

Question 6

A developer wants to run a specific test class using a 'test' profile, which configures an in-memory database defined in an `application-test.properties` file. How can they ensure this profile is activated for just that one test class?

Accepted Answer

By annotating the test class with `@ActiveProfiles("test")`.

Answer

By adding `spring.profiles.active=test` to the main `application.properties` file.

Answer

By annotating the test class with `@Profile("test")`.

Answer

By passing a command-line argument `-Dspring.profiles.active=test` when running the test.