fix: respect TERM=dumb and NO_COLOR for ANSI escape codes

[mvanhorn]

Summary

Skips ANSI escape codes in PrettyPrintErrorMessage when TERM=dumb or NO_COLOR is set.

Why this matters

PrettyPrintErrorMessage in nilaway.go:61 unconditionally wraps error text with ANSI color codes (\x1b[31m for red, \x1b[95m for magenta, etc.). In terminals that don't support ANSI (like Emacs shell mode, some CI runners, or TERM=dumb), these appear as raw escape sequences in the output (#105).

Changes

• nilaway.go: Added an early return in PrettyPrintErrorMessage that checks os.Getenv("TERM") == "dumb" and os.Getenv("NO_COLOR") != "" before applying ANSI codes. When either is set, returns plain text with "error: " prefix but no escape sequences. Also follows the NO_COLOR convention.

Testing

go build ./... passes. The change is a 4-line guard at the top of an existing function. The existing -pretty-print=false flag is unaffected - it controls whether PrettyPrintErrorMessage is called at all (nilaway.go:47-48).

Fixes #105

This contribution was developed with AI assistance (Claude Code).

[CLAassistant]

All committers have signed the CLA.

[vincent067]

This looks like a good issue for a first-time contributor. I'd be happy to work on respecting TERM=dumb and NO_COLOR environment variables. Could you assign this to me?

[mvanhorn]

Hey @vincent067 — this is actually the PR that addresses #105 (TERM=dumb / NO_COLOR support). It's been sitting waiting for maintainer review since March. If you're looking for a first-time contribution on nilaway, the issue tracker has a few open ones you could pick up. Review/testing on this PR would also be welcome if you want to dig in here.

[yuxincs]

Hey, thanks for the contributions!

Perhaps a better place to do this is at https://github.com/uber-go/nilaway/blob/main/config/config.go#L167 where we calculate the default value (currently it's always true, but we can make that respect the terminal envs)? This way if user wants to override it by giving the -pretty-print flag it would still be effective

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 87.21%. Comparing base (c2da117) to head (561326c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
config/config.go	50.00%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #412      +/-   ##
==========================================
- Coverage   87.25%   87.21%   -0.04%     
==========================================
  Files          72       72              
  Lines        8306     8312       +6     
==========================================
+ Hits         7247     7249       +2     
- Misses        867      869       +2     
- Partials      192      194       +2     

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[github-actions]

Golden Test

Note

✅ NilAway errors reported on standard libraries are identical.

2570 errors on base branch (main, c2da117)
2570 errors on test branch (db2ed0b)

[mvanhorn]

Thanks @yuxincs, that is a much better placement. Pushed 234b235:

• Added defaultPrettyPrint() helper in config/config.go that returns false when NO_COLOR is set or TERM=dumb
• Used it as the default for the -pretty-print flag (around line 165)
• Reverted the env check from PrettyPrintErrorMessage in nilaway.go

The override path through pass.Analyzer.Flags.Lookup(PrettyPrintFlag) is untouched, so explicit -pretty-print=true still wins. Tests pass locally; lint fetch failed in my sandbox (network), so CI golangci-lint will be the source of truth there.