Testing a production Bash script: 38 tests without a framework

The context: a Bash script to display Claude Code rate limits in a terminal status bar. At first it seems trivial — a few functions, reading a JSON file, some formatting. But the script quickly ends up handling: JSON parsing with jq , time formatting with timezone, percentage calculations, Unicode progress bar generation, countdown logic. And above all: several edge cases (missing data, corrupted JSON, quotas at 0, unknown timezone). Without tests, every change becomes a lottery. You change the