[test] Add tests for logger error paths: MarkdownLogger.Close, FileLogger.Log, Logger.Print

[github-actions]

Test Coverage Improvement: logger error-handling paths

Functions Analyzed

Function	Package	Previous Coverage	New Coverage
MarkdownLogger.Close	internal/logger	85.7%	100%
MarkdownLogger.initializeFile	internal/logger	87.5%	100%
FileLogger.Log	internal/logger	85.7%	100%
Logger.Print	internal/logger	91.7%	100%
MarkdownLogger.Log	internal/logger	92.3%	96.2%

Overall logger package: 97.6% → 98.6%

Why These Functions?

Five related functions in internal/logger had the lowest coverage in the buildable package set, all with untested error-handling branches:

• MarkdownLogger.Close (85.7%) — the footer WriteString error path was never exercised; the implementation correctly falls through to closeLogFile even when the footer write fails
• MarkdownLogger.initializeFile (87.5%) — the header WriteString error path; the function should return the error and leave ml.initialized = false
• FileLogger.Log (85.7%) — the Sync() error path; a WARNING: Failed to sync log file message should be emitted to stderr
• Logger.Print (91.7%) — the disabled-logger early-return branch; calling Print on a logger with no DEBUG match was never tested

Tests Added

• ✅ TestMarkdownLogger_Close_FooterWriteError — triggers footer write failure by pre-closing the underlying *os.File
• ✅ TestMarkdownLogger_Close_NilLogFile — exercises the logFile == nil branch (fallback/no-file mode)
• ✅ TestMarkdownLogger_InitializeFile_WriteError — triggers header write failure via closed file
• ✅ TestMarkdownLogger_InitializeFile_AlreadyInitialized — fast-path no-op when already initialized
• ✅ TestMarkdownLogger_Log_WriteError — body write failure after successful header init
• ✅ TestMarkdownLogger_Log_NilLogFile — silent drop when logFile is nil
• ✅ TestFileLogger_Log_SyncError — sync warning path via closed file
• ✅ TestLogger_Print_Disabled — early return when logger is disabled

Technique

All error paths are triggered by closing the underlying *os.File before calling the function, causing subsequent OS operations to return os.ErrClosed. Tests are in package logger (white-box) to allow direct struct construction and field access without requiring additional exported helpers.

Coverage Report

Before: 97.6% logger package coverage
After:  98.6% logger package coverage
Improvement: +1.0%

MarkdownLogger.Close:       85.7% → 100%  (+14.3%)
MarkdownLogger.initializeFile: 87.5% → 100%  (+12.5%)
FileLogger.Log:             85.7% → 100%  (+14.3%)
Logger.Print:               91.7% → 100%  ( +8.3%)
MarkdownLogger.Log:         92.3% → 96.2% ( +3.9%)

Test Execution

All 8 new tests pass:

=== RUN   TestMarkdownLogger_Close_FooterWriteError
--- PASS: TestMarkdownLogger_Close_FooterWriteError (0.00s)
=== RUN   TestMarkdownLogger_Close_NilLogFile
--- PASS: TestMarkdownLogger_Close_NilLogFile (0.00s)
=== RUN   TestMarkdownLogger_InitializeFile_WriteError
--- PASS: TestMarkdownLogger_InitializeFile_WriteError (0.00s)
=== RUN   TestMarkdownLogger_InitializeFile_AlreadyInitialized
--- PASS: TestMarkdownLogger_InitializeFile_AlreadyInitialized (0.00s)
=== RUN   TestMarkdownLogger_Log_WriteError
--- PASS: TestMarkdownLogger_Log_WriteError (0.00s)
=== RUN   TestMarkdownLogger_Log_NilLogFile
--- PASS: TestMarkdownLogger_Log_NilLogFile (0.00s)
=== RUN   TestFileLogger_Log_SyncError
--- PASS: TestFileLogger_Log_SyncError (0.00s)
=== RUN   TestLogger_Print_Disabled
--- PASS: TestLogger_Print_Disabled (0.00s)
PASS
ok      github.com/github/gh-aw-mcpg/internal/logger   0.008s

---

Generated by Test Coverage Improver
Next run will target the next most complex under-tested function

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Generated by Test Coverage Improver · sonnet46 9.9M · ◷

[Copilot]

Pull request overview

This PR improves internal/logger test coverage by adding white-box tests for logger error-handling and disabled-output paths without changing production code.

Changes:

• Adds tests for MarkdownLogger.Close, initializeFile, and Log fallback/error branches.
• Adds coverage for FileLogger.Log sync-error handling.
• Adds coverage for Logger.Print when disabled by an empty DEBUG setting.

Show a summary per file

File	Description
internal/logger/markdown_logger_close_coverage_test.go	Adds focused logger coverage tests for markdown, file, and debug logger error/disabled paths.

Copilot's findings

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• Files reviewed: 1/1 changed files
• Comments generated: 2

[lpcox]

@copilot fix the failing lint ci check

[Copilot]

@copilot fix the failing lint ci check

Fixed in fe37fcf — gofmt was applied to internal/logger/markdown_logger_close_coverage_test.go. make lint now passes cleanly.