feat(browser): implement experimental browser agent (#19284)

2026-04-29 14:34:55 -07:00 · 2026-02-24 09:22:09 -08:00
parent 182c858e67
commit 9e95b8b3c5
23 changed files with 3506 additions and 1 deletions
@@ -0,0 +1,196 @@
+/**
+ * @license
+ * Copyright 2026 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { createMcpDeclarativeTools } from './mcpToolWrapper.js';
+import type { BrowserManager, McpToolCallResult } from './browserManager.js';
+import type { MessageBus } from '../../confirmation-bus/message-bus.js';
+import type { Tool as McpTool } from '@modelcontextprotocol/sdk/types.js';
+
+describe('mcpToolWrapper', () => {
+  let mockBrowserManager: BrowserManager;
+  let mockMessageBus: MessageBus;
+  let mockMcpTools: McpTool[];
+
+  beforeEach(() => {
+    vi.resetAllMocks();
+
+    // Setup mock MCP tools discovered from server
+    mockMcpTools = [
+      {
+        name: 'take_snapshot',
+        description: 'Take a snapshot of the page accessibility tree',
+        inputSchema: {
+          type: 'object',
+          properties: {
+            verbose: { type: 'boolean', description: 'Include details' },
+          },
+        },
+      },
+      {
+        name: 'click',
+        description: 'Click on an element by uid',
+        inputSchema: {
+          type: 'object',
+          properties: {
+            uid: { type: 'string', description: 'Element uid' },
+          },
+          required: ['uid'],
+        },
+      },
+    ];
+
+    // Setup mock browser manager
+    mockBrowserManager = {
+      getDiscoveredTools: vi.fn().mockResolvedValue(mockMcpTools),
+      callTool: vi.fn().mockResolvedValue({
+        content: [{ type: 'text', text: 'Tool result' }],
+      } as McpToolCallResult),
+    } as unknown as BrowserManager;
+
+    // Setup mock message bus
+    mockMessageBus = {
+      publish: vi.fn().mockResolvedValue(undefined),
+      subscribe: vi.fn(),
+      unsubscribe: vi.fn(),
+    } as unknown as MessageBus;
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('createMcpDeclarativeTools', () => {
+    it('should create declarative tools from discovered MCP tools', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      expect(tools).toHaveLength(3);
+      expect(tools[0].name).toBe('take_snapshot');
+      expect(tools[1].name).toBe('click');
+      expect(tools[2].name).toBe('type_text');
+    });
+
+    it('should return tools with correct description', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      // Descriptions include augmented hints, so we check they contain the original
+      expect(tools[0].description).toContain(
+        'Take a snapshot of the page accessibility tree',
+      );
+      expect(tools[1].description).toContain('Click on an element by uid');
+    });
+
+    it('should return tools with proper FunctionDeclaration schema', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const schema = tools[0].schema;
+      expect(schema.name).toBe('take_snapshot');
+      expect(schema.parametersJsonSchema).toBeDefined();
+    });
+  });
+
+  describe('McpDeclarativeTool.build', () => {
+    it('should create invocation that can be executed', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[0].build({ verbose: true });
+
+      expect(invocation).toBeDefined();
+      expect(invocation.params).toEqual({ verbose: true });
+    });
+
+    it('should return invocation with correct description', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[0].build({});
+
+      expect(invocation.getDescription()).toContain('take_snapshot');
+    });
+  });
+
+  describe('McpToolInvocation.execute', () => {
+    it('should call browserManager.callTool with correct params', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[1].build({ uid: 'elem-123' });
+      await invocation.execute(new AbortController().signal);
+
+      expect(mockBrowserManager.callTool).toHaveBeenCalledWith(
+        'click',
+        {
+          uid: 'elem-123',
+        },
+        expect.any(AbortSignal),
+      );
+    });
+
+    it('should return success result from MCP tool', async () => {
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[0].build({ verbose: true });
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.llmContent).toBe('Tool result');
+      expect(result.error).toBeUndefined();
+    });
+
+    it('should handle MCP tool errors', async () => {
+      vi.mocked(mockBrowserManager.callTool).mockResolvedValue({
+        content: [{ type: 'text', text: 'Element not found' }],
+        isError: true,
+      } as McpToolCallResult);
+
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[1].build({ uid: 'invalid' });
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.error).toBeDefined();
+      expect(result.error?.message).toBe('Element not found');
+    });
+
+    it('should handle exceptions during tool call', async () => {
+      vi.mocked(mockBrowserManager.callTool).mockRejectedValue(
+        new Error('Connection lost'),
+      );
+
+      const tools = await createMcpDeclarativeTools(
+        mockBrowserManager,
+        mockMessageBus,
+      );
+
+      const invocation = tools[0].build({});
+      const result = await invocation.execute(new AbortController().signal);
+
+      expect(result.error).toBeDefined();
+      expect(result.error?.message).toBe('Connection lost');
+    });
+  });
+});