API reliability starts with tests. We implement unit and integration testing for all key API components: from validation of incoming data to interaction with databases, cache and external services. This provides predictability, stability, and rapid early error detection.
Unit-tests
Unit tests test isolated parts of code, for example:- handlers and controllers
- to the business logician
- validation functions
- serialization and deserialization of data
We use: Jest, Mocha, Pytest, PHPUnit, JUnit, Go Test, etc.
Integration tests
Integration tests test the interaction between modules and components:- API ↔ DB ↔ Cache
- API ↔ external services (e.g. payments, notifications)
- Operation of middleware, authorization, routes
- Full scripts from request to response
We use: Postman, Supertest, Testcontainers, Docker Compose, Pact, etc.
How we organize the process
Structured Test System (unit/integration/e2e)
Autorun tests via CI/CD pipeline
Test data and isolated sandbox environments
Code Coverage and Stability Reports
Release blocking when critical tests fall
Product benefits
Fewer bugs with new releases
Fast error localization
Confidence in API behavior under different loads
Reduced manual check time
Reliable base for writing e2e and contract tests
Where especially important
Critical APIs: Finance, Medical, Government Platforms
Applications with high release rates
Multi-dependency microservice architecture
Commands with CI/CD processes and automatic depletion
Unit and integration tests are a guarantee that the API works exactly as intended. We will help you implement a sustainable testing strategy that ensures quality and reliability at every stage of development.