Spring Boot Testing

What it does

This skill generates Spring Boot 4 unit and integration tests based on your existing code context. It leverages modern testing patterns and best practices, including AssertJ-style assertions for improved readability and MockMvcTester and RestTestClient as alternatives to older approaches. The skill aims to help you write focused and efficient tests by guiding you towards the appropriate test slice for different scenarios (controller, repository, REST client, JSON serialization, or full application).

When to use it

• Testing controller endpoints: When verifying HTTP semantics and controller behavior.
• Validating JPA queries: When ensuring data persistence logic functions correctly.
• Testing interactions with external APIs: When confirming that a REST client integrates properly with external services.
• Verifying JSON serialization/deserialization: When validating the correct mapping of objects to and from JSON format.
• Running full application integration tests: For comprehensive testing of your Spring Boot application.

Key capabilities

• Generates tests using annotations like @WebMvcTest, @DataJpaTest, @RestClientTest, @JsonTest, and @SpringBootTest.
• Supports MockMvcTester for AssertJ-style assertions in web layer tests.
• Utilizes RestTestClient as a modern alternative to TestRestTemplate.
• Provides guidance on selecting the appropriate test slice based on the scenario.
• Offers references and documentation for various testing tools including Testcontainers, MockitoBean, and Instancio.

Example prompts

• "Generate a unit test for this controller endpoint."
• "Create an integration test for this repository method."
• "Show me how to test the JSON serialization of this class."
• "What's the best way to test this REST client interaction?"

Tips & gotchas

• The skill is designed for Spring Boot 4 applications. Migration considerations may apply when upgrading from older versions (see references/sb4-migration.md).
• Consider the Test Pyramid principle: prioritize unit tests over integration tests for faster feedback and focused testing.
• If a method or class requires more than 5-7 test cases, it might be too complex and should be refactored.