Kafka testing

I've talked with 100s of companies about how they test apps on Kafka. I almost always hear the same thing:

1. We have lots of services.

2. It's easy to test one service, but hard to test them all together.

3. Every team tests their service in a different way.

4. Production data usually can't be used for tests (PII, network access, not in prod yet)

5. It's very hard to test future, speculative production traffic.

⚡ I'm all in favor of testing with production data when you can. But for everything else, simulation testing rules.