test: add unit tests for Durable Object and clean up test setup

- Add CanvasRoom broadcast/close/error tests with mock WebSockets
- Remove @cloudflare/vitest-pool-workers (incompatible with Vitest 4)
- Clean up vitest config (single config, no integration workspace)
- 71 tests across 7 test files, all passing

test/durable-objects/canvas-room.test.js

@@ -0,0 +1,99 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { CanvasRoom } from '../../src/durable-objects/canvas-room.js';
+
+/** Create a mock WebSocket */
+function mockWebSocket() {
+  return { send: vi.fn(), close: vi.fn() };
+}
+
+/** Create a mock Durable Object state with Hibernation API */
+function mockState() {
+  const sockets = new Set();
+  return {
+    acceptWebSocket: vi.fn((ws) => sockets.add(ws)),
+    getWebSockets: vi.fn(() => [...sockets]),
+    _sockets: sockets,
+  };
+}
+
+describe('CanvasRoom', () => {
+  let state;
+  let room;
+
+  beforeEach(() => {
+    state = mockState();
+    room = new CanvasRoom(state);
+  });
+
+  describe('broadcast', () => {
+    it('sends pixel data to all connected WebSockets', async () => {
+      const ws1 = mockWebSocket();
+      const ws2 = mockWebSocket();
+      state._sockets.add(ws1);
+      state._sockets.add(ws2);
+
+      const pixels = [{ x: 10, y: 20, color: 5 }];
+      const req = new Request('http://internal/broadcast', {
+        method: 'POST',
+        body: JSON.stringify(pixels),
+      });
+
+      const res = await room.fetch(req);
+      expect(res.status).toBe(200);
+
+      const expected = JSON.stringify({ type: 'pixels', pixels });
+      expect(ws1.send).toHaveBeenCalledWith(expected);
+      expect(ws2.send).toHaveBeenCalledWith(expected);
+    });
+
+    it('closes WebSocket on send failure', async () => {
+      const ws = mockWebSocket();
+      ws.send.mockImplementation(() => { throw new Error('disconnected'); });
+      state._sockets.add(ws);
+
+      const req = new Request('http://internal/broadcast', {
+        method: 'POST',
+        body: JSON.stringify([{ x: 0, y: 0, color: 1 }]),
+      });
+
+      const res = await room.fetch(req);
+      expect(res.status).toBe(200);
+      expect(ws.close).toHaveBeenCalledWith(1011, 'send failed');
+    });
+
+    it('broadcasts to empty room without error', async () => {
+      const req = new Request('http://internal/broadcast', {
+        method: 'POST',
+        body: JSON.stringify([]),
+      });
+
+      const res = await room.fetch(req);
+      expect(res.status).toBe(200);
+    });
+  });
+
+  describe('webSocketClose', () => {
+    it('closes the WebSocket with given code and reason', () => {
+      const ws = mockWebSocket();
+      room.webSocketClose(ws, 1000, 'normal', true);
+      expect(ws.close).toHaveBeenCalledWith(1000, 'normal');
+    });
+  });
+
+  describe('webSocketError', () => {
+    it('closes the WebSocket with error code', () => {
+      const ws = mockWebSocket();
+      room.webSocketError(ws, new Error('test'));
+      expect(ws.close).toHaveBeenCalledWith(1011, 'error');
+    });
+  });
+
+  describe('webSocketMessage', () => {
+    it('ignores messages (no-op)', () => {
+      const ws = mockWebSocket();
+      // Should not throw
+      room.webSocketMessage(ws, 'hello');
+      expect(ws.send).not.toHaveBeenCalled();
+    });
+  });
+});