test-guard

test-guard

AI-assisted test-after framework, packaged as a Claude Code plugin. Bundles skills, a subagent, a hook, and an MCP server so that new code ships with tests and coverage gaps stay visible.

Built around the conventions of a Yarn-workspaces monorepo with a packages/shared package tested by Vitest (pure logic: utils + Redux Toolkit slices).

What's inside

Component	Type	Purpose
write-tests	skill	Author colocated Vitest tests with the repo's exact conventions (RTK reducers, native-module mocking, env/timer/global stubbing). Auto-triggers when you touch pure-logic files.
bug-repro	skill	Fix bugs test-first: write a failing repro test, confirm red, fix, confirm green.
test-writer	agent	Batch-retrofit tests for untested files; runs the suite and iterates to green.
PostToolUse hook	hook	After editing a shared source file with no colocated test, reminds Claude to add one. Never blocks.
test-guard MCP	mcp	list_untested_files, run_tests, coverage_report — each also writes a JSON result to <project>/.test-guard/.

Install (from your GitHub fork)

claude plugin marketplace add <github-user>/test-guard
claude plugin install test-guard@test-guard

After install, set env vars for your repo (add to ~/.zshrc or ~/.bashrc):

export TG_WORKSPACE="@myorg/shared"      # yarn workspace package name (required)
export TG_SHARED_DIR="packages/shared"   # path from project root to tested package (required)
export TG_SCAN_DIRS="utils,redux"        # dirs to scan for untested files (default: utils,redux)
export TG_TEST_RUNNER="vitest run"       # test runner cmd inside workspace (default: vitest run)

Local development

claude --plugin-dir /path/to/test-guard
claude plugin validate /path/to/test-guard

MCP dependencies

The MCP server needs @modelcontextprotocol/sdk + zod. A SessionStart hook runs npm install in the plugin dir once if node_modules is missing. To install manually:

cd /path/to/test-guard && npm install

MCP tools

• list_untested_files — scans packages/shared/{utils,redux} for .ts/.tsx source files lacking a colocated *.test.ts. → .test-guard/untested.json
• run_tests (optional pattern) — runs yarn workspace @myorg/shared vitest run and returns a pass/fail summary. → .test-guard/results.json
• coverage_report — runs Vitest v8 coverage and returns per-file/total %. → .test-guard/coverage.json

Add .test-guard/ to your project's .gitignore.

Tuning for another repo

The shared-package path (packages/shared), workspace name (@myorg/shared), and scanned dirs (utils, redux) are referenced in mcp/server.mjs and the skills. Adjust those constants/paths to retarget the plugin.