add tests for internal stdio transport

Author: JReinhold

packages/mcp/bin.test.ts

@@ -0,0 +1,187 @@
+/**
+ * Integration tests for the stdio MCP server in bin.ts
+ *
+ * These tests spawn the bin.ts process as a child process and communicate
+ * with it via stdin/stdout, simulating how an MCP client would interact
+ * with the server in production.
+ */
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { x } from 'tinyexec';
+import { resolve, dirname } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import type { ChildProcess } from 'node:child_process';
+
+/**
+ * Helper to send a JSON-RPC request and wait for the response
+ */
+async function sendRequest(
+	child: ChildProcess,
+	stdoutData: string[],
+	request: unknown,
+	requestId: number,
+	timeoutMs = 10_000,
+): Promise<unknown> {
+	// Send request
+	child.stdin?.write(JSON.stringify(request) + '\n');
+
+	// Wait for response with timeout
+	const { promise, resolve, reject } = Promise.withResolvers<void>();
+	const timeout = setTimeout(() => {
+		reject(new Error(`Timeout waiting for response to request ${requestId}`));
+	}, timeoutMs);
+
+	const checkResponse = () => {
+		const allData = stdoutData.join('');
+		if (allData.includes(`"id":${requestId}`)) {
+			clearTimeout(timeout);
+			resolve();
+		} else {
+			setTimeout(checkResponse, 50);
+		}
+	};
+	checkResponse();
+
+	await promise;
+
+	// Parse and return the response
+	const allData = stdoutData.join('');
+	const lines = allData.split('\n').filter((line) => line.trim());
+	const responseLine = lines.find((line) => {
+		try {
+			const parsed = JSON.parse(line);
+			return parsed.id === requestId;
+		} catch {
+			return false;
+		}
+	});
+
+	if (!responseLine) {
+		throw new Error(`No response found for request ${requestId}`);
+	}
+
+	return JSON.parse(responseLine);
+}
+
+describe('bin.ts stdio MCP server', () => {
+	let child: ChildProcess;
+	let stdoutData: string[] = [];
+	let stderrData: string[] = [];
+
+	beforeAll(() => {
+		const currentDir = dirname(fileURLToPath(import.meta.url));
+		const binPath = resolve(currentDir, './bin.ts');
+		const fixturePath = resolve(
+			currentDir,
+			'./fixtures/full-manifest.fixture.json',
+		);
+
+		const proc = x('node', [binPath, '--manifestPath', fixturePath]);
+
+		child = proc.process as ChildProcess;
+
+		// Collect stdout for later assertions
+		child.stdout?.on('data', (chunk) => {
+			stdoutData.push(chunk.toString());
+		});
+
+		// Collect stderr for debugging
+		child.stderr?.on('data', (chunk) => {
+			stderrData.push(chunk.toString());
+		});
+
+		child.on('error', (err) => {
+			console.error('Process error:', err);
+		});
+	});
+
+	afterAll(() => {
+		child.kill();
+	});
+
+	it('should respond to initialize request', async () => {
+		const request = {
+			jsonrpc: '2.0',
+			id: 1,
+			method: 'initialize',
+			params: {
+				protocolVersion: '2024-11-05',
+				capabilities: {},
+				clientInfo: {
+					name: 'test-client',
+					version: '1.0.0',
+				},
+			},
+		};
+
+		const response = await sendRequest(child, stdoutData, request, 1);
+
+		expect(response).toMatchObject({
+			jsonrpc: '2.0',
+			id: 1,
+			result: {
+				protocolVersion: '2024-11-05',
+				capabilities: {
+					tools: {
+						listChanged: true,
+					},
+				},
+				serverInfo: {
+					name: '@storybook/mcp',
+				},
+			},
+		});
+	}, 15000);
+
+	it('should list available tools', async () => {
+		const request = {
+			jsonrpc: '2.0',
+			id: 2,
+			method: 'tools/list',
+			params: {},
+		};
+
+		const response = await sendRequest(child, stdoutData, request, 2);
+
+		expect(response).toMatchObject({
+			jsonrpc: '2.0',
+			id: 2,
+			result: {
+				tools: expect.arrayContaining([
+					expect.objectContaining({
+						name: 'list-all-components',
+					}),
+					expect.objectContaining({
+						name: 'get-component-documentation',
+					}),
+				]),
+			},
+		});
+	}, 15000);
+
+	it('should execute list-all-components tool', async () => {
+		const request = {
+			jsonrpc: '2.0',
+			id: 3,
+			method: 'tools/call',
+			params: {
+				name: 'list-all-components',
+				arguments: {},
+			},
+		};
+
+		const response = await sendRequest(child, stdoutData, request, 3);
+
+		expect(response).toMatchObject({
+			jsonrpc: '2.0',
+			id: 3,
+			result: {
+				content: [
+					{
+						type: 'text',
+						text: expect.stringContaining('<components>'),
+					},
+				],
+			},
+		});
+	}, 15000);
+});

packages/mcp/package.json

@@ -41,6 +41,7 @@
 	"devDependencies": {
 		"@tmcp/transport-stdio": "catalog:",
 		"react-docgen": "^8.0.2",
-		"srvx": "^0.8.16"
+		"srvx": "^0.8.16",
+		"tinyexec": "^1.0.2"
 	}
 }