test: 添加完整测试套件（52 个文件，326 个用例）

基于 Vitest 搭建测试基础设施，覆盖后端纯函数、API 路由、
前端 hooks、UI 组件和页面级集成测试。

src/app/api/blindbox/draw/route.test.ts

@@ -0,0 +1,99 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { prismaMock, resetPrismaMock } from "@/__tests__/helpers/prisma-mock";
+import { createRequest, parseJsonResponse } from "@/__tests__/helpers/api-test-utils";
+import { TEST_USER } from "@/__tests__/helpers/fixtures";
+
+vi.mock("@/lib/blindbox", () => ({
+  requireMembership: vi.fn().mockResolvedValue({}),
+}));
+
+import { POST } from "./route";
+
+const mockCtx = { params: Promise.resolve({}) };
+
+beforeEach(() => {
+  resetPrismaMock();
+});
+
+describe("POST /api/blindbox/draw", () => {
+  it("draws a random idea", async () => {
+    prismaMock.$transaction.mockImplementation(async (fn: (tx: unknown) => Promise<unknown>) => {
+      const tx = {
+        blindBoxIdea: {
+          findMany: vi.fn().mockResolvedValue([{ id: "idea-1" }]),
+          updateMany: vi.fn().mockResolvedValue({ count: 1 }),
+          findUnique: vi.fn().mockResolvedValue({
+            id: "idea-1",
+            content: "去公园",
+            createdAt: new Date(),
+            user: { id: "user-2", username: "submitter", avatar: "🐶" },
+            drawnBy: { id: "user-1", username: "drawer", avatar: "🐱" },
+          }),
+        },
+      };
+      return fn(tx);
+    });
+
+    const req = createRequest("/api/blindbox/draw", {
+      method: "POST",
+      body: { roomId: "bb-room-1", userId: "user-1" },
+    });
+    const res = await POST(req, mockCtx);
+    const { status, data } = await parseJsonResponse(res);
+
+    expect(status).toBe(200);
+    expect(data.id).toBe("idea-1");
+    expect(data.content).toBe("去公园");
+    expect(data.submitter).toBeDefined();
+    expect(data.drawnBy).toBeDefined();
+  });
+
+  it("returns 404 when pool is empty", async () => {
+    prismaMock.$transaction.mockImplementation(async (fn: (tx: unknown) => Promise<unknown>) => {
+      const tx = {
+        blindBoxIdea: {
+          findMany: vi.fn().mockResolvedValue([]),
+          updateMany: vi.fn(),
+          findUnique: vi.fn(),
+        },
+      };
+      return fn(tx);
+    });
+
+    const req = createRequest("/api/blindbox/draw", {
+      method: "POST",
+      body: { roomId: "bb-room-1", userId: "user-1" },
+    });
+    const res = await POST(req, mockCtx);
+    expect(res.status).toBe(404);
+  });
+
+  it("returns 409 on race condition (count=0)", async () => {
+    prismaMock.$transaction.mockImplementation(async (fn: (tx: unknown) => Promise<unknown>) => {
+      const tx = {
+        blindBoxIdea: {
+          findMany: vi.fn().mockResolvedValue([{ id: "idea-1" }]),
+          updateMany: vi.fn().mockResolvedValue({ count: 0 }),
+          findUnique: vi.fn(),
+        },
+      };
+      return fn(tx);
+    });
+
+    const req = createRequest("/api/blindbox/draw", {
+      method: "POST",
+      body: { roomId: "bb-room-1", userId: "user-1" },
+    });
+    const res = await POST(req, mockCtx);
+    expect(res.status).toBe(409);
+  });
+
+  it("returns 400 when roomId is missing", async () => {
+    const req = createRequest("/api/blindbox/draw", {
+      method: "POST",
+      body: { userId: "user-1" },
+    });
+    const res = await POST(req, mockCtx);
+    expect(res.status).toBe(400);
+  });
+});