Testing Pyramid

The testing pyramid organizes tests by scope and speed:

• Unit tests (bottom, many): Test individual functions in isolation.
• Integration tests (middle): Test modules/services together.
• Contract/CDC tests (middle): Test API contracts between services.
• System/E2E tests (upper): Test complete user flows.
• Acceptance/UAT (top, few): Validate against business requirements.

Each level builds on the previous: unit tests catch bugs early and fast; system tests validate end-to-end.

📄️ Unit Testing

Test individual functions and classes in isolation.

📄️ Component and Integration Testing

Test service boundaries and data flows with component tests, API contract tests, database integration tests, and test containers for reproducible environments.

📄️ Contract and Consumer-Driven Contract Tests

Validate API contracts between services to catch breaking changes early and enable safe microservices development.

📄️ End-to-End and System Testing

Test complete user workflows across all system layers to validate real-world behavior and user experience.

📄️ Acceptance and User Acceptance Testing (UAT)

Validate that the system meets business requirements and user expectations using behavior-driven testing frameworks.