---
description: Testing
globs: **/*.{test,spec}.ts
alwaysApply: false
---

- Follow the Arrange-Act-Assert convention for tests.
- Use Jest for unit and integration tests
- Mock dependencies with `@nestjs/testing`
- Test controllers and services separately
- Achieve high test coverage (>80% coverage)
- Name test variables clearly.
  - Follow the convention: inputX, mockX, actualX, expectedX, etc.
- Write unit tests for each public function.
  - Use test doubles to simulate dependencies.
    - Except for third-party dependencies that are not expensive to execute.
- Write acceptance tests for each module.
  - Follow the Given-When-Then convention.

## Database Testing Best Practices

- Use Testcontainers for integration tests
  - Spin up real database instances (PostgreSQL, MySQL, MongoDB, etc.)
  - Ensures tests run against actual database engines
  - Example: `@testcontainers/postgresql` for PostgreSQL testing
- Create isolated test databases
  - Each test suite should use a separate database/schema
  - Prevents test interference and ensures clean state
  - Use unique database names with timestamps or UUIDs
- Implement proper test data seeding
  - Create factories for test data generation
  - Use fixtures for consistent test scenarios
  - Clear and seed database before each test suite
  - Example: Use TypeORM factories or custom seed scripts
- Transaction rollback strategy
  - Wrap each test in a transaction that rolls back
  - Maintains database cleanliness between tests
  - Faster than truncating tables
- E2E testing with real databases
  - Use Docker Compose for multi-container setups
  - Include all required services (Redis, Elasticsearch, etc.)
  - Mirror production environment as closely as possible