Exit non-zero when a run fails, is aborted, or cannot parse its arguments [patch]

[matt-edmondson]

Fixes #144

Before: Main and every verb returned void, so the process exited 0 for a missing directory, an abort, failed deletions and unknown options. Deduplicate -p /data && echo done reported success even when nothing was deleted.

After, measured against the built dll:

Command	Exit code
Scan -p /nonexistent	1
Scan -p <a file>	1
Scan --nope	2
--help	0
Scan -p <dir>	0
echo n | Deduplicate -p <dir with duplicates>	1

How:

• Main returns int and goes through Program.Run(parser, args), which uses ParseArguments(...).MapResult(...). A parse failure returns 2. Asking for help or the version returns 0.

• BaseVerb.Run() returns the exit code, and ICommand.Execute (the menu) discards it. BaseVerb<T>.Run returns 1 in two cases:

  • the path prompt is aborted
  • the root is missing or isn't a directory, checked by the new FileScanner.IsScannableDirectory before the verb runs

  Otherwise it returns the verb's ExitCode, which starts at 0. Deduplicate sets it to 1 when the user declines or a deletion fails. Menu opts out of the root check.

• Scan, DryRun and Stats are unchanged. Putting the exit code in their bodies added lines inside the scan pipeline that all four verbs copy (Scan, DryRun, Deduplicate and Stats each copy the path prompt and the scan→hash→group pipeline, so every fix to that path must be made four times #157), and SonarCloud failed the first push on 10.5% duplication on new code.

• ExitCodeTests covers each case, including a real command line through Program.Run. With BaseVerb<T>.Run and Main forced back to returning 0, six of them fail.

• The deletion-failure test is inconclusive as root, the same as the existing ACopyThatCannotBeDeletedIsReportedAndTheRunCarriesOn. I ran both as nobody and both passed.

Not covered: an unknown verb (FileDeduplicator Nope) still falls through to the default Menu verb rather than exiting 2. That's the path #161 is about.

This branches from main, separately from #169 (for #145). Both touch BaseVerb, so whichever merges second may need a small merge.

Tests: 77 total, 74 passed, 3 skipped (the permission-staging tests, which can't stage the failure as root).

🤖 Generated with Claude Code

https://claude.ai/code/session_01U5RBnMaTjZdMDRNttjeZ3u

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
82.4% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud