Feat/more test coverage

[muhahahmad68]

Overview

Achieves 90%+ branch coverage on the self-upgrade utilities in internal/updater, covering all previously untested error paths, HTTP integration branches, cache failure modes, and configuration parsing edge cases.

Changes

Core Implementation

• checker.go: Added apiURL string field to Checker struct
  • One-line branch in fetchLatestVersion uses apiURL when set, falls back to GitHubAPIURL
  • Enables full HTTP path testing without hitting the real GitHub API
  • Zero behaviour change for production callers — NewChecker never sets apiURL

Testing

• checker_coverage_test.go: New test file covering all 23 previously-uncovered branches

  fetchLatestVersion

  • Success path returns correct tag name with proper User-Agent header
  • Non-200 status (403, 429) returns structured error
  • Malformed JSON body returns parse error
  • Dead server (connection refused) returns network error
  • Cancelled context returns context error

  compareVersions

  • Unparseable current version returns error
  • Unparseable latest version returns error

  updateCache

  • File blocking cache directory returns MkdirAll error
  • Read-only cache directory returns WriteFile error
  • Both cases skipped when running as root

  CheckForUpdates integration

  • Update available → notification printed to stderr
  • No update needed → no output produced
  • API error → no output, no panic
  • Disabled by ERST_NO_UPDATE_CHECK → API never called
  • Fresh cache → API never called

  checkConfigFile

  • check_for_updates: true does not disable
  • No matching key does not disable
  • Empty file does not disable
  • Comment line is skipped
  • Value with surrounding whitespace is handled correctly
  • Multiple keys, false value is respected

  isUpdateCheckDisabled

  • Empty configPath fallthrough returns false without panic

  getCacheDir / getConfigPath

  • Always return a non-empty path containing erst on supported platforms
  • Neither panics under any environment

Coverage

• All code paths tested without lint suppressions
• Tests are hermetic: every test that touches the filesystem uses t.TempDir()
• Every test that sets environment variables uses t.Setenv() for automatic cleanup
• HTTP tests use httptest.NewServer — no network required

Verification

go test ./internal/updater/... -v -count=1
go test ./internal/updater/... -coverprofile=coverage.out
go tool cover -func=coverage.out | grep total

Related Issues

Closes #425

Type of Change

• New feature
• Bug fix
• Breaking change
• Test coverage improvement

Checklist

• Code follows project style guidelines
• Self-review completed
• Tests added — 23 new branch paths covered
• No new linting issues
• No lint suppressions added
• All tests are hermetic (no shared state, no real network calls)
• Backward compatible — apiURL field is unexported and zero-valued in production

[dotandev]

fix conflicts, please.