Java + SpringBoot : Robust API endpoints with testcontainers | S Labs Solutions

Unit Tests
- cover the logic of a module. It verifies if the features work as expected for valid and invalid inputs. It is independent and fast.
- Used with Test Driven Development(TDD) for feature addition and refactoring existing code
Integration Tests
- Cover the end-to-end flow of an application.
- It spins up the entire application and verifies the integration of modules

Code - https://github.com/slabstech/tutorials/

Steps
- To verify API with manual tests
  - Use Swagger/OpenAPI to Generate API documentation using
    - Spring 2.x - ‘org.springdoc:springdoc-openapi-ui’
    - Spring 3.x - ‘org.springdoc:springdoc-openapi-starter-webmvc-ui’
  - Create test.http with sample inputs for manual verification
- To verify API with Integration Tests
  - Use Testcontainers
    - ‘org.testcontainers:junit-jupiter’, ‘org.springframework.boot:spring-boot-testcontainers’, ‘org.springframework.boot:spring-boot-starter-test’
    - Use different container for each use case. Ex
      - Database tests
        
        PostgreSQL Container -
      - Kafka Container -
        
        KafkaContainer kafka = new KafkaContainer(DockerImageName.parse(“confluentinc/cp-kafka:6.2.1”))
- To verify Modules with Unit Tests
  - Validate models/data with Bean validation
    - ‘org.springframework.boot:spring-boot-starter-validation’
Reference
- SpringBoot
  - https://github.com/testcontainers/testcontainers-java/tree/main/examples/spring-boot
- Database Integration Test
  - https://java.testcontainers.org/modules/databases/postgres/
  - https://www.baeldung.com/spring-boot-testcontainers-integration-test
- Kafka
  - https://www.baeldung.com/spring-boot-kafka-testing
- Docker Compose
  - https://java.testcontainers.org/modules/docker_compose/
  - https://www.baeldung.com/persistence-with-spring-series