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… test reliability - watch_manager: wrap _add_template_triggers in try/except within the infra sync error handler to prevent the watch process from crashing when the template is unparseable during error recovery - testing_utils: add descriptive message to bare ValueError in read_until, and catch ValueError in read_until_string to include expected output context - test_sync_adl: increase layer sync timeouts from 60s to 120s - test_sync_watch: increase nested stack infra sync timeout to 900s
seshubaws
approved these changes
Feb 13, 2026
vicheey
approved these changes
Feb 13, 2026
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Problem
Four sync integration tests were failing:
TestSyncWatchInfraWithInvalidTemplate::test_sync_watch_infra- ValueError: The watch process crashed when an invalid template was applied duringsam sync --watch.TestSyncAdlWithWatchStartWithNoDependencies::test_sync_watch_code- TimeoutError (60s): Layer sync operations exceeded the 60s timeout.TestSyncInfraNestedStacks_0::test_sync_watch_infra_nested_stack- TimeoutError (600s): Nested stack infra sync exceeded the 600s timeout.TestSyncInfraNestedStacks_1::test_sync_watch_infra_nested_stack- TimeoutError (600s): Same as above.Root Cause
The
ValueErrorwas caused by an unhandled exception inwatch_manager.py. When infra sync fails (e.g., invalid template), the error handler calls_add_template_triggers()to re-register file watchers. However,_add_template_triggers()callsSamLocalStackProvider.get_stacks()which can also throw if the template is unparseable. This unhandled exception propagated up and crashed the watch process's main loop, causing the process to exit.The
TimeoutErrorfailures were due to timeouts that were too tight for the operations being performed.Fix
samcli/lib/sync/watch_manager.py: Wrap_add_template_triggers()in try/except within the infra sync error handler so the watch process survives and can recover when the template is fixed.tests/testing_utils.py: Add descriptive message to the bareraise ValueError()inread_until, and catchValueErrorinread_until_stringto include expected output context for better debugging.tests/integration/sync/test_sync_adl.py: Increase layer sync timeouts from 60s to 120s.tests/integration/sync/test_sync_watch.py: Increase nested stack infra sync timeout from 600s to 900s.Testing
Verified with real AWS deployments on fork — all 4 tests passed in two consecutive runs: