n8n-enterprise-unlocked/packages/@n8n/nodes-langchain/nodes/mcp/McpClientTool/McpClientTool.node.test.ts

import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { SSEClientTransport } from '@modelcontextprotocol/sdk/client/sse.js';
import { mock } from 'jest-mock-extended';
import {
	NodeOperationError,
	type ILoadOptionsFunctions,
	type INode,
	type ISupplyDataFunctions,
} from 'n8n-workflow';

import { getTools } from './loadOptions';
import { McpClientTool } from './McpClientTool.node';
import { McpToolkit } from './utils';

jest.mock('@modelcontextprotocol/sdk/client/sse.js');
jest.mock('@modelcontextprotocol/sdk/client/index.js');

describe('McpClientTool', () => {
	describe('loadOptions: getTools', () => {
		it('should return a list of tools', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool',
						description: 'MyTool does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
				],
			});

			const result = await getTools.call(
				mock<ILoadOptionsFunctions>({ getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })) }),
			);

			expect(result).toEqual([
				{
					description: 'MyTool does something',
					name: 'MyTool',
					value: 'MyTool',
				},
			]);
		});

		it('should handle errors', async () => {
			jest.spyOn(Client.prototype, 'connect').mockRejectedValue(new Error('Fail!'));

			const node = mock<INode>({ typeVersion: 1 });
			await expect(
				getTools.call(mock<ILoadOptionsFunctions>({ getNode: jest.fn(() => node) })),
			).rejects.toEqual(new NodeOperationError(node, 'Could not connect to your MCP server'));
		});
	});

	describe('supplyData', () => {
		beforeEach(() => {
			jest.resetAllMocks();
		});

		it('should return a valid toolkit with usable tools (that returns a string)', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest
				.spyOn(Client.prototype, 'callTool')
				.mockResolvedValue({ content: [{ type: 'text', text: 'result from tool' }] });
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool1',
						description: 'MyTool1 does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
					{
						name: 'MyTool2',
						description: 'MyTool2 does something',
						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
					},
				],
			});

			const supplyDataResult = await new McpClientTool().supplyData.call(
				mock<ISupplyDataFunctions>({
					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
					logger: { debug: jest.fn(), error: jest.fn() },
					addInputData: jest.fn(() => ({ index: 0 })),
				}),
				0,
			);

			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);

			const tools = (supplyDataResult.response as McpToolkit).getTools();
			expect(tools).toHaveLength(2);

			const toolCallResult = await tools[0].invoke({ input: 'foo' });
			expect(toolCallResult).toEqual(JSON.stringify([{ type: 'text', text: 'result from tool' }]));
		});

		it('should support selecting tools to expose', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool1',
						description: 'MyTool1 does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
					{
						name: 'MyTool2',
						description: 'MyTool2 does something',
						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
					},
				],
			});

			const supplyDataResult = await new McpClientTool().supplyData.call(
				mock<ISupplyDataFunctions>({
					getNode: jest.fn(() =>
						mock<INode>({
							typeVersion: 1,
						}),
					),
					getNodeParameter: jest.fn((key, _index) => {
						const parameters: Record<string, any> = {
							include: 'selected',
							includeTools: ['MyTool2'],
						};
						return parameters[key];
					}),
					logger: { debug: jest.fn(), error: jest.fn() },
					addInputData: jest.fn(() => ({ index: 0 })),
				}),
				0,
			);

			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);

			const tools = (supplyDataResult.response as McpToolkit).getTools();
			expect(tools).toHaveLength(1);
			expect(tools[0].name).toBe('MyTool2');
		});

		it('should support selecting tools to exclude', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool1',
						description: 'MyTool1 does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
					{
						name: 'MyTool2',
						description: 'MyTool2 does something',
						inputSchema: { type: 'object', properties: { input2: { type: 'string' } } },
					},
				],
			});

			const supplyDataResult = await new McpClientTool().supplyData.call(
				mock<ISupplyDataFunctions>({
					getNode: jest.fn(() =>
						mock<INode>({
							typeVersion: 1,
						}),
					),
					getNodeParameter: jest.fn((key, _index) => {
						const parameters: Record<string, any> = {
							include: 'except',
							excludeTools: ['MyTool2'],
						};
						return parameters[key];
					}),
					logger: { debug: jest.fn(), error: jest.fn() },
					addInputData: jest.fn(() => ({ index: 0 })),
				}),
				0,
			);

			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);

			const tools = (supplyDataResult.response as McpToolkit).getTools();
			expect(tools).toHaveLength(1);
			expect(tools[0].name).toBe('MyTool1');
		});

		it('should support header auth', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool1',
						description: 'MyTool1 does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
				],
			});

			const supplyDataResult = await new McpClientTool().supplyData.call(
				mock<ISupplyDataFunctions>({
					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
					getNodeParameter: jest.fn((key, _index) => {
						const parameters: Record<string, any> = {
							include: 'except',
							excludeTools: ['MyTool2'],
							authentication: 'headerAuth',
							sseEndpoint: 'https://my-mcp-endpoint.ai/sse',
						};
						return parameters[key];
					}),
					logger: { debug: jest.fn(), error: jest.fn() },
					addInputData: jest.fn(() => ({ index: 0 })),
					getCredentials: jest.fn().mockResolvedValue({ name: 'my-header', value: 'header-value' }),
				}),
				0,
			);

			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);

			const fetchSpy = jest.spyOn(global, 'fetch').mockResolvedValue(mock());
			const url = new URL('https://my-mcp-endpoint.ai/sse');
			expect(SSEClientTransport).toHaveBeenCalledTimes(1);
			expect(SSEClientTransport).toHaveBeenCalledWith(url, {
				eventSourceInit: { fetch: expect.any(Function) },
				requestInit: { headers: { 'my-header': 'header-value' } },
			});

			const customFetch = jest.mocked(SSEClientTransport).mock.calls[0][1]?.eventSourceInit?.fetch;
			await customFetch?.(url);
			expect(fetchSpy).toHaveBeenCalledWith(url, {
				headers: { Accept: 'text/event-stream', 'my-header': 'header-value' },
			});
		});

		it('should support bearer auth', async () => {
			jest.spyOn(Client.prototype, 'connect').mockResolvedValue();
			jest.spyOn(Client.prototype, 'listTools').mockResolvedValue({
				tools: [
					{
						name: 'MyTool1',
						description: 'MyTool1 does something',
						inputSchema: { type: 'object', properties: { input: { type: 'string' } } },
					},
				],
			});

			const supplyDataResult = await new McpClientTool().supplyData.call(
				mock<ISupplyDataFunctions>({
					getNode: jest.fn(() => mock<INode>({ typeVersion: 1 })),
					getNodeParameter: jest.fn((key, _index) => {
						const parameters: Record<string, any> = {
							include: 'except',
							excludeTools: ['MyTool2'],
							authentication: 'bearerAuth',
							sseEndpoint: 'https://my-mcp-endpoint.ai/sse',
						};
						return parameters[key];
					}),
					logger: { debug: jest.fn(), error: jest.fn() },
					addInputData: jest.fn(() => ({ index: 0 })),
					getCredentials: jest.fn().mockResolvedValue({ token: 'my-token' }),
				}),
				0,
			);

			expect(supplyDataResult.closeFunction).toBeInstanceOf(Function);
			expect(supplyDataResult.response).toBeInstanceOf(McpToolkit);

			const fetchSpy = jest.spyOn(global, 'fetch').mockResolvedValue(mock());
			const url = new URL('https://my-mcp-endpoint.ai/sse');
			expect(SSEClientTransport).toHaveBeenCalledTimes(1);
			expect(SSEClientTransport).toHaveBeenCalledWith(url, {
				eventSourceInit: { fetch: expect.any(Function) },
				requestInit: { headers: { Authorization: 'Bearer my-token' } },
			});

			const customFetch = jest.mocked(SSEClientTransport).mock.calls[0][1]?.eventSourceInit?.fetch;
			await customFetch?.(url);
			expect(fetchSpy).toHaveBeenCalledWith(url, {
				headers: { Accept: 'text/event-stream', Authorization: 'Bearer my-token' },
			});
		});
	});
});