Testing and Replay Tests

Unit tests, time-skipping, replaying production histories against new code

Three kinds of tests: Workflow tests in the time-skipping environment (a three-day Workflow finishes in milliseconds), Activity tests, and replay tests that take histories from production and replay them under new code to catch non-determinism before deploy. Then failure injection: Worker crash, Activity timeout, duplicate execution, cancellation.

Estimated time: 90 minutes

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