integration-testing_skill

Overview

This skill defines integration testing standards for API testing, database testing, and service-to-service communication. It provides practical patterns for Testcontainers, Docker Compose, API mocking, and contract testing to build reliable, reproducible integration suites. The goal is fast feedback, real interactions, and environment isolation so teams catch integration regressions early.

How this skill works

The skill prescribes running tests against real dependencies in isolated containers (Postgres, Redis, message brokers) using Testcontainers or Docker Compose. It recommends exercising real HTTP endpoints, applying contract tests (Pact) between consumers and providers, and using WireMock/MockServer for external service stubs. Migrations, fixtures, and cleanup routines ensure consistent state between runs.

When to use it

• Validation of end-to-end flows that cross service or database boundaries
• Before merging changes that affect APIs, schemas, or inter-service contracts
• In CI pipelines to catch integration regressions early
• When verifying database migrations, rollbacks, and data integrity
• While developing new integrations with third-party APIs or message queues

Best practices

• Run tests in ephemeral, isolated containers (Testcontainers or Docker Compose) to ensure reproducibility
• Prefer real HTTP calls and real databases for integration tests; mock only external third-party behavior
• Keep tests fast and focused—split slow integration scenarios and run them in a dedicated pipeline stage
• Define and verify provider-consumer contracts using Pact or similar tools to avoid API drift
• Manage test data explicitly with fixtures, migrations, and teardown to avoid flaky results

Example use cases

• Spin up Postgres and Redis via Testcontainers to run user CRUD integration tests against the running app
• Use WireMock to stub external payment provider responses when testing checkout flows
• Publish and verify Pact files between a frontend consumer and API gateway provider in CI
• Compose a full test environment with docker-compose.test.yml to run end-to-end smoke tests
• Automate migration validation by running schema changes against a containerized database and asserting rollbacks