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/**
* @license
* Copyright 2025 Google LLC
* SPDX-License-Identifier: Apache-2.0
*/
import { afterEach, describe, expect, it, vi, beforeEach } from 'vitest';
import { StreamableHTTPClientTransport } from '@modelcontextprotocol/sdk/client/streamableHttp.js';
import {
populateMcpServerCommand,
createTransport,
isEnabled,
discoverTools,
} from './mcp-client.js';
import { SSEClientTransport } from '@modelcontextprotocol/sdk/client/sse.js';
import * as SdkClientStdioLib from '@modelcontextprotocol/sdk/client/stdio.js';
import * as ClientLib from '@modelcontextprotocol/sdk/client/index.js';
import * as GenAiLib from '@google/genai';
vi.mock('@modelcontextprotocol/sdk/client/stdio.js');
vi.mock('@modelcontextprotocol/sdk/client/index.js');
vi.mock('@google/genai');
describe('mcp-client', () => {
afterEach(() => {
vi.restoreAllMocks();
});
describe('discoverTools', () => {
it('should discover tools', async () => {
const mockedClient = {} as unknown as ClientLib.Client;
const mockedMcpToTool = vi.mocked(GenAiLib.mcpToTool).mockReturnValue({
tool: () => ({
functionDeclarations: [
{
name: 'testFunction',
},
],
}),
} as unknown as GenAiLib.CallableTool);
const tools = await discoverTools('test-server', {}, mockedClient);
expect(tools.length).toBe(1);
expect(mockedMcpToTool).toHaveBeenCalledOnce();
});
});
describe('appendMcpServerCommand', () => {
it('should do nothing if no MCP servers or command are configured', () => {
const out = populateMcpServerCommand({}, undefined);
expect(out).toEqual({});
});
it('should discover tools via mcpServerCommand', () => {
const commandString = 'command --arg1 value1';
const out = populateMcpServerCommand({}, commandString);
expect(out).toEqual({
mcp: {
command: 'command',
args: ['--arg1', 'value1'],
},
});
});
it('should handle error if mcpServerCommand parsing fails', () => {
expect(() => populateMcpServerCommand({}, 'derp && herp')).toThrowError();
});
});
describe('createTransport', () => {
const originalEnv = process.env;
beforeEach(() => {
vi.resetModules();
process.env = {};
});
afterEach(() => {
process.env = originalEnv;
});
describe('should connect via httpUrl', () => {
it('without headers', async () => {
const transport = createTransport(
'test-server',
{
httpUrl: 'http://test-server',
},
false,
);
expect(transport).toEqual(
new StreamableHTTPClientTransport(new URL('http://test-server'), {}),
);
});
it('with headers', async () => {
const transport = createTransport(
'test-server',
{
httpUrl: 'http://test-server',
headers: { Authorization: 'derp' },
},
false,
);
expect(transport).toEqual(
new StreamableHTTPClientTransport(new URL('http://test-server'), {
requestInit: {
headers: { Authorization: 'derp' },
},
}),
);
});
});
describe('should connect via url', () => {
it('without headers', async () => {
const transport = createTransport(
'test-server',
{
url: 'http://test-server',
},
false,
);
expect(transport).toEqual(
new SSEClientTransport(new URL('http://test-server'), {}),
);
});
it('with headers', async () => {
const transport = createTransport(
'test-server',
{
url: 'http://test-server',
headers: { Authorization: 'derp' },
},
false,
);
expect(transport).toEqual(
new SSEClientTransport(new URL('http://test-server'), {
requestInit: {
headers: { Authorization: 'derp' },
},
}),
);
});
});
it('should connect via command', () => {
const mockedTransport = vi.mocked(SdkClientStdioLib.StdioClientTransport);
createTransport(
'test-server',
{
command: 'test-command',
args: ['--foo', 'bar'],
env: { FOO: 'bar' },
cwd: 'test/cwd',
},
false,
);
expect(mockedTransport).toHaveBeenCalledWith({
command: 'test-command',
args: ['--foo', 'bar'],
cwd: 'test/cwd',
env: { FOO: 'bar' },
stderr: 'pipe',
});
});
});
describe('isEnabled', () => {
const funcDecl = { name: 'myTool' };
const serverName = 'myServer';
it('should return true if no include or exclude lists are provided', () => {
const mcpServerConfig = {};
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(true);
});
it('should return false if the tool is in the exclude list', () => {
const mcpServerConfig = { excludeTools: ['myTool'] };
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(false);
});
it('should return true if the tool is in the include list', () => {
const mcpServerConfig = { includeTools: ['myTool'] };
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(true);
});
it('should return true if the tool is in the include list with parentheses', () => {
const mcpServerConfig = { includeTools: ['myTool()'] };
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(true);
});
it('should return false if the include list exists but does not contain the tool', () => {
const mcpServerConfig = { includeTools: ['anotherTool'] };
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(false);
});
it('should return false if the tool is in both the include and exclude lists', () => {
const mcpServerConfig = {
includeTools: ['myTool'],
excludeTools: ['myTool'],
};
expect(isEnabled(funcDecl, serverName, mcpServerConfig)).toBe(false);
});
it('should return false if the function declaration has no name', () => {
const namelessFuncDecl = {};
const mcpServerConfig = {};
expect(isEnabled(namelessFuncDecl, serverName, mcpServerConfig)).toBe(
false,
);
});
});
});
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