𝗖𝗼𝗻𝘁𝗿𝗮𝗰𝘁 𝗧𝗲𝘀𝘁𝗶𝗻𝗴 𝘄𝗶𝘁𝗵 𝗣𝗮𝗰𝘁
Integration testing for microservices is hard. End to end tests are slow. Mock tests pass alone but fail in production. Contract testing solves this.
It verifies how two services talk. You test each side separately. The consumer defines needs in a contract. The provider verifies these needs.
Pact is a tool for this. The consumer writes a test for the API call and response. Pact creates a contract file. The provider runs this file against the API.
This approach gives you control. The consumer defines requirements. The provider must meet them.
Put this in your CI pipeline. Consumer tests make contracts on every build. Contracts go to a Pact Broker. Provider tests check the latest contracts. The build fails if a change breaks the contract.
Contract testing catches these bugs:
- Missing fields.
- Renamed fields.
- Wrong data types.
- Changed response formats.
These tests run in milliseconds. They are more reliable than end to end tests.
Start with your most critical services. Focus on APIs with frequent changes. Use this when services have different deployment cycles.
This does not replace end to end tests. It gives you faster feedback.