Integration testing challenges in microservices

[mike ross]

I’ve been working on a microservices based application and running into issues that don’t show up in unit tests.

Individually, services work fine, but when they interact, I see problems like timeouts, mismatched responses, or unexpected failures between APIs. Debugging these issues is getting difficult because everything works in isolation.

I’m trying to understand how others approach integration testing in such setups. Do you rely on real service interactions, mocks, or some hybrid approach?

I came across this explanation on integration testing which helped me understand the basics, but I’d like to hear practical approaches from experienced developers:

https://keploy.io/blog/community/integration-testing-a-comprehensive-guide

How do you structure integration tests in distributed systems without slowing down development?

[robert02]

We use a hybrid approach:

• Contract tests (Pact) for service interactions
• Testcontainers for real dependencies (DB, Kafka, etc.)
• Lightweight Docker Compose for key end-to-end flows

Avoids over-mocking while keeping tests fast. Full system tests only for critical paths.

This cut down most of our integration surprises.