Due to Standalone Activities, testActivityToken are used to keep track of activities, instead of just activityID, they now contain activityID and runID. Most users should not be affected, only if you're manually constructing task tokens in your tests.
Versioning v1 and v2 worker options and versioning intent have been marked as deprecated.
Properly set RootWorkflowExecution in child workflow env when testing.
Enforcement of heartbeat and start-to-close timeouts in test environment, as well as properly cancel timer when AwaitWithTimeout condition resolves.
Full Changelog: https://github.com/temporalio/sdk-go/compare/v1.39.0...v1.40.0
Fetched April 11, 2026