If you ever worked on a system with a few tens of microservices you got to a point where making changes become difficult. You always worry something is going to break. Unit tests are not enough. You need to have a way to test if (for example) the HTTP request to register a user will trigger that welcome e-mail at the end of the flow.

So we've build an open source framework where you can simply write such tests. You can assert on database queries, on HTTP requests and responses, and more to come. We use traces from OpenTelemetry to verify that the assertions you wrote in your test are true.

Our long term goal is to even generate the tests automatically from those traces.

We're still early on so would love to get any feedback on our concept and implementation!

repo: https://github.com/traceloop/jest-opentelemetry

docs: https://docs.traceloop.dev/jest-otel/introduction