feat(wave3): @mosaic/quality-rails TypeScript scaffolder (#8)

Co-authored-by: Jason Woltje <jason@diversecanvas.com>
Co-committed-by: Jason Woltje <jason@diversecanvas.com>

packages/quality-rails/tests/detect.test.ts

@@ -0,0 +1,40 @@
+import { mkdtemp, rm, writeFile } from 'node:fs/promises';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+
+import { describe, expect, it } from 'vitest';
+
+import { detectProjectKind } from '../src/detect.js';
+
+async function withTempDir(run: (directory: string) => Promise<void>): Promise<void> {
+  const directory = await mkdtemp(join(tmpdir(), 'quality-rails-detect-'));
+  try {
+    await run(directory);
+  } finally {
+    await rm(directory, { recursive: true, force: true });
+  }
+}
+
+describe('detectProjectKind', () => {
+  it('returns node when package.json exists', async () => {
+    await withTempDir(async (directory) => {
+      await writeFile(join(directory, 'package.json'), '{"name":"fixture"}\n', 'utf8');
+
+      await expect(detectProjectKind(directory)).resolves.toBe('node');
+    });
+  });
+
+  it('returns python when pyproject.toml exists and package.json does not', async () => {
+    await withTempDir(async (directory) => {
+      await writeFile(join(directory, 'pyproject.toml'), '[project]\nname = "fixture"\n', 'utf8');
+
+      await expect(detectProjectKind(directory)).resolves.toBe('python');
+    });
+  });
+
+  it('returns unknown when no known project files exist', async () => {
+    await withTempDir(async (directory) => {
+      await expect(detectProjectKind(directory)).resolves.toBe('unknown');
+    });
+  });
+});