Testing Temporal Workflows#

Temporal workflows have a property that most distributed systems lack: determinism. A workflow function, given the same inputs and the same sequence of activity results, will always produce the same output. This makes workflows far more testable than you might expect for code that orchestrates long-running, multi-step processes.

Activities are the opposite. They talk to databases, call APIs, read files, and produce side effects. You do not want your unit tests doing any of that. The testing strategy follows directly: test workflows by mocking their activities, and test activities by injecting mock dependencies.

Testing Strategies in CI Pipelines#

Every CI pipeline faces the same tension: run enough tests to catch bugs before they merge, but not so many that developers wait twenty minutes for feedback on a one-line change. The answer is not running everything everywhere. It is running the right tests at the right time.

The Three Test Tiers#

Tests divide into three tiers based on execution speed, failure signal quality, and infrastructure requirements.