test(01-01): add failing health test (RED gate)

- Tests GET /health returns 200 { ok, db } on success and 503 on DB error
- Fails because src/index.ts and src/routes/health.ts don't exist yet

apps/api/tests/health.test.ts

@@ -1,16 +1,50 @@
 /**
- * Wave 0 stub — GET /health: 200 + real DB round-trip
+ * GET /health — end-to-end skeleton test
  *
- * This test is a RED stub. Implementation lives in:
+ * TDD RED: Tests written before implementation.
- *   apps/api/src/routes/health.ts  (Task 2)
+ * These will fail until Task 2 creates apps/api/src/routes/health.ts
+ * and apps/api/src/index.ts.
  *
- * The test will be filled GREEN in Task 2 when the health route is implemented.
+ * Behavior (from plan):
+ *   - GET /health returns 200 with { ok: true, db: "up" } after a real DB round-trip
+ *   - GET /health returns 503 if the DB round-trip throws
  */
 
-import { describe, it } from 'vitest'
+import { describe, it, expect, vi, beforeEach } from 'vitest'
+
+// We test the health route by importing the Hono app and calling it directly
+// (no real DB needed — we mock the db module)
 
 describe('GET /health', () => {
-  it.todo('returns 200 with { ok: true, db: "up" } after a real DB round-trip (Task 2)')
+  beforeEach(() => {
+    vi.resetModules()
+  })
 
-  it.todo('returns 503 if the DB round-trip throws (Task 2)')
+  it('returns 200 with { ok: true, db: "up" } when DB round-trip succeeds', async () => {
+    // Mock the db module so no real MariaDB is needed
+    vi.mock('../src/db/client.js', () => ({
+      db: {
+        execute: vi.fn().mockResolvedValue([[]]),
+      },
+    }))
+
+    const { app } = await import('../src/index.js')
+    const res = await app.request('/health')
+    expect(res.status).toBe(200)
+    const body = await res.json()
+    expect(body.ok).toBe(true)
+    expect(body.db).toBe('up')
+  })
+
+  it('returns 503 when DB round-trip throws', async () => {
+    vi.mock('../src/db/client.js', () => ({
+      db: {
+        execute: vi.fn().mockRejectedValue(new Error('DB connection failed')),
+      },
+    }))
+
+    const { app } = await import('../src/index.js')
+    const res = await app.request('/health')
+    expect(res.status).toBe(503)
+  })
 })