test: add unit tests for logger and update check utils

[ZayanKhan-12]

Why

src/utils/logger.ts and src/utils/check-for-updates.ts had no unit test coverage in tests/utils/. Both contain observable behavior (file log sink, namespace enabling, flush timeout, update cache freshness/once-per-process logic) that can regress silently, so this adds focused tests asserting the current behavior. No src/ changes.

What's covered

tests/utils/logger.test.ts (6 tests)

• saveLogsToFile writes mcp:log output to the given file, appends (flag a+) instead of truncating, writes one newline-terminated line per log call, and enables the mcp:log debug namespace even when previously disabled.
• flushLogs resolves once the stream has finished, and rejects when the stream does not finish within the timeout (via a stub stream whose end callback never fires).
• Global debug state (enabled namespaces, debug.log sink) is saved and restored around the suite.

tests/utils/check-for-updates.test.ts (8 tests)

• Early return when CHROME_DEVTOOLS_MCP_NO_UPDATE_CHECKS is set (the test runner sets this globally, so the tests save/clear/restore it).
• First run with no cache: writes {version: VERSION} to ~/.cache/chrome-devtools-mcp/latest.json and spawns check-latest-version.js detached with stdio: 'ignore'.
• Warns with Update available: <current> -> <cached> plus the caller-provided message when the cached version is newer; no warning when equal.
• Fresh cache (<24h): no re-check spawn, cache untouched. Stale cache (>24h): re-check spawn, mtime refreshed, content preserved.
• Invalid-JSON cache is ignored without throwing.
• Once-per-process guard, including resetUpdateCheckFlagForTesting().
• Tests redirect os.homedir() to a per-test temp dir and stub child_process.spawn/console.warn via node:test's mock.method, so no real home-directory files are touched and no subprocess/network activity happens.

What's not covered (and why)

• saveLogsToFile's stream error handler calls process.exit(1), which cannot be exercised in-process without killing the test runner.
• The spawned bin/check-latest-version.js subprocess itself (registry fetch) is out of scope for these unit tests; spawn is stubbed.
• Observation (not asserted, no behavior change made): while logs are redirected to a file, debug.log is replaced with a plain chunks.join(' ') sink, so printf-style placeholders (e.g. logger('hello %s', 'world')) are written literally as hello %s world instead of being substituted the way the default util.formatWithOptions-based sink does. The tests use plain messages to assert current behavior; happy to file a follow-up issue if that quirk is worth fixing.

Testing

• npm run build — clean.
• node scripts/test.js tests/utils/logger.test.ts tests/utils/check-for-updates.test.ts — 14/14 pass.
• npm run test:no-build — 702 tests, 702 pass, 0 fail.
• npm run check-format — eslint + prettier clean.

🤖 Generated with Claude Code

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[Lightning00Blade]

This is a side-effect and we should not test for it.

[Lightning00Blade]

There is test in tests/check-for-updates.test.ts Why do we need this?