Summary

When running E2E tests against LocalStack, CloudFormation stack deletion fails with a template validation error, even for minimal stacks that don't have the referenced resource.

Error

An error occurred (ValidationError) when calling the DeleteStack operation: 
Template format error: Unresolved resource dependencies [AggregatorDLQ] in the Resources block of the template

Root Cause

LocalStack appears to be caching or confusing templates. A minimal stack (DynamoDB table only, no aggregator) fails deletion with an error referencing AggregatorDLQ which only exists in full stacks with aggregator enabled.

Investigation

# List stack resources - shows only DynamoDB table (minimal stack)
aws cloudformation describe-stack-resources --stack-name zae-limiter-e2e_test_xxx

# But deletion fails with error about AggregatorDLQ
aws cloudformation delete-stack --stack-name zae-limiter-e2e_test_xxx

Workaround

The E2E test fixtures wrap delete_stack() in try/except to handle this gracefully:

try:
    await limiter.delete_stack()
except Exception as e:
    # LocalStack may have issues with stack deletion, log but don't fail
    print(f"Warning: Stack cleanup failed: {e}")

Resources can be deleted directly as a workaround:

aws dynamodb delete-table --table-name e2e_test_xxx

Impact

• Test stacks accumulate in LocalStack during E2E test runs
• Not a blocker for testing (tests pass)
• Would not affect real AWS deployments

Notes

This may be related to LocalStack's CloudFormation implementation or template caching behavior. Consider reporting upstream to LocalStack if this persists.