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ValidationStopStopWhen the agent finishes its task· non-blocking

Run tests at end of response

Won't hand back until the test suite is green

When the agent finishes its response, runs the test suite. If tests fail, sends the agent back to work to fix them before handing back control.

What does the Run tests at end of response hook do?

Run tests at end of response is a Claude Code Stop hook. It fires automatically at that lifecycle event — outside the model, so it can't be skipped or forgotten. Won't hand back until the test suite is green.

Use cases

  • Assisted TDD
  • Regression safety net
  • Quality before handoff

Tags

#validation#tests#ci#quality

settings.json fragment

{
  "hooks": {
    "Stop": [
      {
        "hooks": [
          {
            "command": "node $CLAUDE_PROJECT_DIR/.claude/hooks/run-tests.mjs",
            "type": "command"
          }
        ]
      }
    ]
  }
}

Script · .claude/hooks/run-tests.mjs

#!/usr/bin/env node
// Exécute la suite de tests à la fin d'une session (Stop)
import { spawnSync, execSync } from 'child_process';
import { existsSync, readFileSync } from 'fs';
import { join } from 'path';
import { fileURLToPath } from 'url';

/** Résout la racine principale du repo (pas le worktree courant). */
function resolveMainRoot(cwd) {
  try {
    const list = execSync('git worktree list', { encoding: 'utf8', cwd, timeout: 5_000 });
    return list.split('\n')[0]?.split(/\s+/)[0] ?? cwd;
  } catch {
    return cwd;
  }
}

// Détecte le runner de tests adapté au projet.
export function detect({ exists = existsSync, readFile = readFileSync, projectDir } = {}) {
  const pkg = join(projectDir, 'package.json');
  if (exists(pkg)) {
    try {
      const scripts = JSON.parse(readFile(pkg, 'utf8')).scripts ?? {};
      if (scripts.test) {
        const mgr = exists(join(projectDir, 'pnpm-lock.yaml')) ? 'pnpm'
          : exists(join(projectDir, 'bun.lockb')) || exists(join(projectDir, 'bun.lock')) ? 'bun'
          : exists(join(projectDir, 'yarn.lock')) ? 'yarn'
          : 'npm';
        // bun test is non-watch by default and doesn't accept --run
        if (mgr === 'bun') return ['bun', ['test']];
        return [mgr, ['test', '--', '--run']];
      }
    } catch {}
  }
  if (exists(join(projectDir, 'pytest.ini')) || exists(join(projectDir, 'pyproject.toml')))
    return ['python', ['-m', 'pytest', '--tb=short', '-q']];
  if (exists(join(projectDir, 'go.mod'))) return ['go', ['test', './...']];
  return null;
}

export function run({
  exists = existsSync,
  readFile = readFileSync,
  spawn = spawnSync,
  projectDir = process.env.CLAUDE_PROJECT_DIR ?? process.cwd(),
  mainRoot = resolveMainRoot(process.env.CLAUDE_PROJECT_DIR ?? process.cwd()),
} = {}) {
  // Dans un worktree secondaire, lancer les tests depuis la racine principale
  // qui contient node_modules.
  const runDir = exists(join(projectDir, 'node_modules')) ? projectDir : mainRoot;
  const runner = detect({ exists, readFile, projectDir: runDir });
  if (!runner) return null;

  const [cmd, args] = runner;
  const result = spawn(cmd, args, {
    cwd: runDir,
    encoding: 'utf8',
    timeout: 120_000,
    stdio: ['ignore', 'pipe', 'pipe'],
    env: { ...process.env, CI: 'true' },
  });

  const out = (result.stdout ?? '') + (result.stderr ?? '');
  let message = `[run-tests] Exécution : ${cmd} ${args.join(' ')}\n`;
  if (result.status !== 0) {
    message += `[run-tests] ÉCHEC (exit ${result.status})\n${out.slice(-2000)}\n`;
  } else {
    const last = out.split('\n').filter(Boolean).slice(-5).join('\n');
    message += `[run-tests] ✓ Tests passés\n${last}\n`;
  }
  return { runner, status: result.status, message };
}

/* v8 ignore next 6 */
if (process.argv[1] === fileURLToPath(import.meta.url)) {
  const result = run();
  if (result) {
    process.stderr.write(result.message);
    if (result.status !== 0) process.exit(2);
  }
}