Not sure about other languages but I believe the stock test tooling for `go` generates a random sorting seed and has a flag to run tests concurrently. You can a

Not sure about other languages but I believe the stock test tooling for `go` generates a random sorting seed and has a flag to run tests concurrently. You can also manually pass the seed to simulate a certain ordering. While not perfect, our e2e tests caught a couple bugs running them with concurrency.