Add tests for LLM API endpoints

jest.setup.ts

@@ -1,8 +1,10 @@
 import '@testing-library/jest-dom'
 
-// Mock scrollIntoView for JSDOM
-window.HTMLElement.prototype.scrollIntoView = jest.fn();
-window.HTMLMediaElement.prototype.play = () => Promise.resolve();
+if (typeof window !== 'undefined') {
+  // Mock scrollIntoView for JSDOM
+  window.HTMLElement.prototype.scrollIntoView = jest.fn();
+  window.HTMLMediaElement.prototype.play = () => Promise.resolve();
+}
 
 // Mock react-markdown to avoid ESM issues in Jest
 jest.mock('react-markdown', () => ({

src/app/api/v1/llm/chat/route.test.ts

@@ -0,0 +1,117 @@
+/**
+ * @jest-environment node
+ */
+import { POST } from "./route";
+import { getGenAIModel } from "@/lib/gemini";
+import { PERSONALITIES } from "@/lib/personalities";
+
+jest.mock("@/lib/gemini", () => ({
+  getGenAIModel: jest.fn(),
+}));
+
+const mockSendMessage = jest.fn();
+const mockStartChat = jest.fn();
+const mockModel = { startChat: mockStartChat };
+
+const makeRequest = (body: any) => ({
+  json: async () => body,
+}) as any;
+
+function setupModelMock(replyText: string) {
+  mockSendMessage.mockResolvedValue({ response: { text: () => replyText } });
+  mockStartChat.mockReturnValue({ sendMessage: mockSendMessage });
+  (getGenAIModel as jest.Mock).mockReturnValue(mockModel);
+}
+
+describe("POST /api/v1/llm/chat", () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+  });
+
+  it("returns 400 when required fields are missing", async () => {
+    setupModelMock("irrelevant");
+
+    const response = await POST(makeRequest({}));
+    const payload = await response.json();
+
+    expect(response.status).toBe(400);
+    expect(payload.error).toBe("Missing apiKey");
+  });
+
+  it("rejects unknown personalities", async () => {
+    setupModelMock("irrelevant");
+
+    const response = await POST(
+      makeRequest({
+        apiKey: "test-key",
+        personalityId: "not-real",
+        language: "en",
+        playerColor: "white",
+        message: "Hello",
+      })
+    );
+
+    const payload = await response.json();
+    expect(response.status).toBe(400);
+    expect(payload.error).toBe("Unknown personality");
+  });
+
+  it("uses server prompts, normalized history, and returns tutor reply", async () => {
+    const personality = PERSONALITIES[0];
+    setupModelMock("Tutor reply");
+
+    const response = await POST(
+      makeRequest({
+        apiKey: "test-key",
+        personalityId: personality.id,
+        language: "en",
+        playerColor: "white",
+        message: "How should I continue?",
+        history: [
+          { role: "user", text: "Previous question" },
+          { role: "model", text: "Previous answer" },
+          { role: "system", text: "ignored" } as any,
+        ],
+        context: {
+          currentFen: "8/8/8/8/8/8/8/8 w - - 0 1",
+          evaluation: { score: 20, mate: null, bestMove: "e4" },
+        },
+      })
+    );
+
+    const payload = await response.json();
+
+    expect(response.status).toBe(200);
+    expect(payload.reply).toBe("Tutor reply");
+
+    expect(getGenAIModel).toHaveBeenCalledWith("test-key", "gemini-2.5-flash");
+
+    expect(mockStartChat).toHaveBeenCalledTimes(1);
+    const startHistory = mockStartChat.mock.calls[0][0].history;
+    expect(startHistory).toHaveLength(4); // 2 system + 2 normalized history entries
+    expect(startHistory[0].parts[0].text).toContain("You are a Chess Tutor");
+
+    expect(mockSendMessage).toHaveBeenCalledTimes(1);
+    const prompt = mockSendMessage.mock.calls[0][0];
+    expect(prompt).toContain("[SYSTEM TRIGGER: user_message]");
+    expect(prompt).toContain("User Message: How should I continue?");
+  });
+
+  it("honors custom model names", async () => {
+    const personality = PERSONALITIES[1];
+    setupModelMock("Another reply");
+
+    await POST(
+      makeRequest({
+        apiKey: "key-123",
+        personalityId: personality.id,
+        language: "en",
+        playerColor: "black",
+        message: "Explain this move",
+        modelName: "gemini-custom",
+      })
+    );
+
+    expect(getGenAIModel).toHaveBeenCalledWith("key-123", "gemini-custom");
+  });
+});

src/app/api/v1/personalities/route.test.ts

@@ -0,0 +1,25 @@
+/**
+ * @jest-environment node
+ */
+import { GET } from "./route";
+import { PERSONALITIES } from "@/lib/personalities";
+
+describe("GET /api/v1/personalities", () => {
+  it("returns sanitized personality metadata", async () => {
+    const response = await GET();
+    const payload = await response.json();
+
+    expect(response.status).toBe(200);
+    expect(Array.isArray(payload.personalities)).toBe(true);
+    expect(payload.personalities).toHaveLength(PERSONALITIES.length);
+    expect(payload.personalities[0]).toEqual(
+      expect.objectContaining({
+        id: expect.any(String),
+        name: expect.any(String),
+        description: expect.any(String),
+        image: expect.any(String),
+      })
+    );
+    expect(payload.personalities[0]).not.toHaveProperty("systemPrompt");
+  });
+});