feat: add allow-empty option to staged command

packages/rstack/src/staged.ts

@@ -1,17 +1,30 @@
+import { parseArgs } from 'node:util';
 import { loadRstackConfig } from './config.js';
 
 const stagedHelpMessage = `Rstack v${RSTACK_VERSION}
 
 Usage:
-  $ rs staged
+  $ rs staged [options]
 
 Runs lint-staged with tasks from define.staged in rstack.config.
 
 Options:
-  -h, --help  Display this help message`;
+  --allow-empty  Allow empty commits when tasks revert all staged changes
+  -h, --help     Display this help message`;
 
 export async function runStagedCLI(args: string[]): Promise<void> {
-  if (args.length === 1 && (args[0] === '-h' || args[0] === '--help')) {
+  const { values } = parseArgs({
+    args,
+    options: {
+      'allow-empty': { type: 'boolean' },
+      allowEmpty: { type: 'boolean' },
+      help: { type: 'boolean', short: 'h' },
+    },
+    allowPositionals: false,
+    strict: true,
+  });
+
+  if (values.help) {
     console.log(stagedHelpMessage);
     return;
   }
@@ -29,6 +42,7 @@ export async function runStagedCLI(args: string[]): Promise<void> {
     'lint-staged'
   );
   const success = await lintStaged({
+    allowEmpty: values['allow-empty'] ?? values.allowEmpty ?? false,
     config: stagedConfig,
   });
   if (!success) {

packages/rstack/test/cli/staged/index.test.ts

@@ -0,0 +1,86 @@
+import { execFileSync } from 'node:child_process';
+import { mkdtemp, rm, writeFile } from 'node:fs/promises';
+import path from 'node:path';
+import { test } from '#test-helpers';
+
+const git = (cwd: string, args: string[]): void => {
+  execFileSync('git', args, { cwd, stdio: 'ignore' });
+};
+
+const createGitFixture = async (): Promise<string> => {
+  const cwd = await mkdtemp(path.join(import.meta.dirname, 'fixture-'));
+
+  await Promise.all([
+    writeFile(
+      path.join(cwd, 'rstack.config.ts'),
+      `import { define } from 'rstack';
+
+define.staged({ '*.txt': 'node revert.mjs' });
+`,
+    ),
+    writeFile(
+      path.join(cwd, 'revert.mjs'),
+      `import { writeFileSync } from 'node:fs';
+
+for (const file of process.argv.slice(2)) {
+  writeFileSync(file, 'initial\\n');
+}
+`,
+    ),
+    writeFile(path.join(cwd, 'file.txt'), 'initial\n'),
+  ]);
+
+  git(cwd, ['init', '--quiet']);
+  git(cwd, ['add', '.']);
+  git(cwd, [
+    '-c',
+    'user.name=Rstack Test',
+    '-c',
+    'user.email=rstack@example.com',
+    'commit',
+    '--quiet',
+    '-m',
+    'initial',
+  ]);
+
+  await writeFile(path.join(cwd, 'file.txt'), 'changed\n');
+  git(cwd, ['add', 'file.txt']);
+
+  return cwd;
+};
+
+const withGitFixture = async (callback: (cwd: string) => Promise<void> | void): Promise<void> => {
+  const cwd = await createGitFixture();
+
+  try {
+    await callback(cwd);
+  } finally {
+    await rm(cwd, { recursive: true, force: true });
+  }
+};
+
+test('should display the staged help message', ({ execCli, expect }) => {
+  const output = execCli('staged --help');
+
+  expect(output).toContain('Rstack v');
+  expect(output).toContain('Usage:\n  $ rs staged [options]');
+  expect(output).toContain('Runs lint-staged with tasks from define.staged in rstack.config.');
+  expect(output).toContain('--allow-empty');
+  expect(output).toContain('-h, --help');
+});
+
+test('should reject unknown staged options', ({ execCli, expect }) => {
+  expect(() => execCli('staged --unknown')).toThrow();
+});
+
+test('should prevent an empty commit by default', async ({ execCli, expect }) => {
+  await withGitFixture((cwd) => {
+    expect(() => execCli('staged', { cwd })).toThrow();
+  });
+});
+
+test(`should allow an empty commit with --allow-empty`, async ({ execCli }) => {
+  await withGitFixture((cwd) => {
+    execCli(`staged --allow-empty`, { cwd });
+  });
+});