Add granular exit codes for different error types

[Copilot]

Implementation Plan: Add Granular Exit Codes

• Define exit code constants in cli.ts
• Implement configuration error handling (exit code 2)
• Implement file read error handling (exit code 3)
• Implement parse error tracking and threshold handling (exit code 4)
• Update CLI to use appropriate exit codes based on error type
• Create tests for exit code behavior
• Update README.md to document exit codes
• Verify all changes work correctly
• Fix CLI code coverage measurement (73% coverage achieved)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add granular exit codes for different error types</issue_title>
<issue_description>## Problem
--fail-on-error exits with code 1 if any URLs found, but can't distinguish error types.

Solution

Add more granular exit codes.

Exit Codes

• 0 - Success, no URLs found
• 1 - URLs found (when --fail-on-error)
• 2 - Configuration error
• 3 - File read error
• 4 - Parse error threshold exceeded

Files to Modify

• src/cli.ts - Set appropriate exit codes
• Update documentation

Priority

Phase 2 - Performance & UX (Medium Impact, Low Effort)

Related to TODO.md section 3.2</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add granular exit codes for different error types #92

---

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[codecov]

Codecov Report

❌ Patch coverage is 72.34043% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.89%. Comparing base (d6edcda) to head (3cef41b).

Files with missing lines	Patch %	Lines
src/cli.ts	72.34%	13 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #114       +/-   ##
===========================================
+ Coverage   49.89%   68.89%   +19.00%     
===========================================
  Files           9        9               
  Lines         487      508       +21     
  Branches      107      116        +9     
===========================================
+ Hits          243      350      +107     
+ Misses        244      158       -86     

Flag	Coverage Δ
unittests	68.89% <72.34%> (+19.00%)	⬆️

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[bingenito]

/allowdco

[bingenito]

@copilot While exitCodes.test.ts tests the new exit codes, the coverage of cli.js remains 0. Identify and resolve issues with coverage of any tests for cli.js not being measured.

[Copilot]

@copilot While exitCodes.test.ts tests the new exit codes, the coverage of cli.js remains 0. Identify and resolve issues with coverage of any tests for cli.js not being measured.

Fixed in commit 3cef41b.

The issue was that exitCodes.test.ts spawns the CLI as a separate Node process, which prevents Jest's coverage instrumentation from measuring the code execution.

Solution:

• Refactored src/cli.ts to extract the main action logic into an exported runCLI() function
• Created tests/cli.test.ts with unit tests that directly call runCLI() instead of spawning a process
• This allows Jest to properly instrument and measure the CLI code

Results:

• CLI coverage increased from 0% to 73%
• Both integration tests (exitCodes.test.ts) and unit tests (cli.test.ts) now pass
• All 100 tests pass successfully

The coverage report now shows:

cli.ts | 73.01% Stmts | 50% Branch | 50% Funcs | 72.58% Lines