Testing Patterns

The best way to structure API testing is to use unit tests for internal logic, integration tests for the API contract, and the Arrange-Act-Assert pattern to ensure robust endpoint coverage.

The test pyramid principle guides software quality by recommending a higher volume of fast unit tests at the base, fewer integration tests in the middle, and a minimal number of end-to-end tests at the top.

To test async code and mock database interactions in TypeScript, apply specific testing patterns that handle asynchronous operations and replace database components with mocked objects to isolate logic.

You need contract testing when you must verify that an API provider and consumer adhere to a shared agreement, which standard integration testing does not explicitly guarantee across separate services.

You should test behavior rather than implementation details to maintain robust test suites that do not break during internal code refactoring, ensuring your tests validate actual software functionality.

Set meaningful test coverage goals by identifying critical application paths first, then targeting those areas with specific integration and unit tests instead of aiming for arbitrary one hundred percent coverage.