Myles/vercel ai sdk migration

.gitignore

@@ -4,3 +4,8 @@ bin
 test-results/
 .envrc
 .specstory/
+
+# Backend env file
+.env
+.env.local
+OpenAiKey

chartsmith-app/app/api/chat/__tests__/route.test.ts

@@ -0,0 +1,230 @@
+/**
+ * Chat API Route Tests
+ * 
+ * Tests for the /api/chat endpoint.
+ * These tests verify request validation and error handling
+ * without making actual API calls to OpenRouter.
+ */
+
+// Suppress console.error during error handling tests (expected errors)
+const originalConsoleError = console.error;
+beforeAll(() => {
+  console.error = jest.fn();
+});
+afterAll(() => {
+  console.error = originalConsoleError;
+});
+
+// Mock the AI SDK before importing the route
+jest.mock('ai', () => ({
+  streamText: jest.fn(),
+  convertToModelMessages: jest.fn((messages) => messages),
+  stepCountIs: jest.fn((count) => ({ type: 'step-count', count })),
+  UIMessage: {},
+}));
+
+jest.mock('@/lib/ai', () => ({
+  getModel: jest.fn(() => ({ modelId: 'test-model' })),
+  isValidProvider: jest.fn((p) => ['anthropic', 'openai'].includes(p)),
+  isValidModel: jest.fn((m) => m.startsWith('anthropic/') || m.startsWith('openai/')),
+  CHARTSMITH_SYSTEM_PROMPT: 'Test system prompt',
+  MAX_STREAMING_DURATION: 60,
+}));
+
+import { POST } from '../route';
+import { streamText } from 'ai';
+import { getModel, isValidProvider, isValidModel } from '@/lib/ai';
+
+describe('POST /api/chat', () => {
+  beforeEach(() => {
+    jest.clearAllMocks();
+
+    // Mock streamText to return a mock response
+    // PR2.0: Route uses toUIMessageStreamResponse (AI SDK v5)
+    (streamText as jest.Mock).mockReturnValue({
+      toUIMessageStreamResponse: () => new Response('streamed response', {
+        headers: { 'Content-Type': 'text/event-stream' },
+      }),
+      toTextStreamResponse: () => new Response('streamed response', {
+        headers: { 'Content-Type': 'text/event-stream' },
+      }),
+    });
+  });
+
+  describe('Request Validation', () => {
+    it('should return 400 if messages array is missing', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({}),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(400);
+      expect(data.error).toBe('Invalid request');
+      expect(data.details).toContain('messages');
+    });
+
+    it('should return 400 if messages is not an array', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({ messages: 'not an array' }),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(400);
+      expect(data.error).toBe('Invalid request');
+    });
+
+    it('should return 400 for invalid provider', async () => {
+      (isValidProvider as jest.Mock).mockReturnValue(false);
+
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+          provider: 'invalid-provider',
+        }),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(400);
+      expect(data.error).toBe('Invalid provider');
+    });
+
+    it('should return 400 for invalid model', async () => {
+      (isValidModel as jest.Mock).mockReturnValue(false);
+
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+          model: 'invalid/model',
+        }),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(400);
+      expect(data.error).toBe('Invalid model');
+    });
+  });
+
+  describe('Successful Requests', () => {
+    beforeEach(() => {
+      (isValidProvider as jest.Mock).mockReturnValue(true);
+      (isValidModel as jest.Mock).mockReturnValue(true);
+    });
+
+    it('should accept valid request with messages only', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+        }),
+      });
+
+      const response = await POST(request);
+
+      expect(response.status).toBe(200);
+      expect(streamText).toHaveBeenCalled();
+    });
+
+    it('should accept valid request with provider', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+          provider: 'anthropic',
+        }),
+      });
+
+      const response = await POST(request);
+
+      expect(response.status).toBe(200);
+      expect(getModel).toHaveBeenCalledWith('anthropic', undefined);
+    });
+
+    it('should accept valid request with provider and model', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+          provider: 'anthropic',
+          model: 'anthropic/claude-sonnet-4',
+        }),
+      });
+
+      const response = await POST(request);
+
+      expect(response.status).toBe(200);
+      expect(getModel).toHaveBeenCalledWith('anthropic', 'anthropic/claude-sonnet-4');
+    });
+
+    it('should return streaming response', async () => {
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+        }),
+      });
+
+      const response = await POST(request);
+
+      expect(response.headers.get('Content-Type')).toBe('text/event-stream');
+    });
+  });
+
+  describe('Error Handling', () => {
+    it('should return 500 for missing API key error', async () => {
+      (isValidProvider as jest.Mock).mockReturnValue(true);
+      (getModel as jest.Mock).mockImplementation(() => {
+        throw new Error('OPENROUTER_API_KEY environment variable is not set');
+      });
+
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+        }),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(500);
+      expect(data.error).toBe('Configuration error');
+    });
+
+    it('should return 500 for unexpected errors', async () => {
+      (isValidProvider as jest.Mock).mockReturnValue(true);
+      (isValidModel as jest.Mock).mockReturnValue(true);
+      // Reset getModel to succeed, but streamText fails
+      (getModel as jest.Mock).mockReturnValue({ modelId: 'test-model' });
+      (streamText as jest.Mock).mockImplementation(() => {
+        throw new Error('Unexpected network error');
+      });
+
+      const request = new Request('http://localhost/api/chat', {
+        method: 'POST',
+        body: JSON.stringify({
+          messages: [{ role: 'user', content: 'Hello' }],
+        }),
+      });
+
+      const response = await POST(request);
+      const data = await response.json();
+
+      expect(response.status).toBe(500);
+      expect(data.error).toBe('Failed to process request');
+      expect(data.details).toContain('network error');
+    });
+  });
+});
+