Extract command status normalization logic from HandleCommandAck into
a dedicated helper function. This improves testability and makes the
status alias handling explicit and documented.
The function accepts client-provided status strings and maps them to
internal status constants:
- acknowledged: "", "ack", "acknowledged"
- completed: "success", "completed", "complete"
- failed: "fail", "failed", "error"
Adds 25 table-driven test cases covering all aliases, case insensitivity,
whitespace handling, and invalid inputs.
