good progress

Author: kentcdodds

epicshop/package-lock.json

@@ -5,6 +5,7 @@
     "@epic-web/workshop-utils": "^5.13.6",
     "chokidar": "^4.0.3",
     "execa": "^9.5.2",
-    "fs-extra": "^11.3.0"
+    "fs-extra": "^11.3.0",
+    "tsx": "^4.19.3"
   }
 }

epicshop/package.json

@@ -4,6 +4,8 @@
   "type": "module",
   "scripts": {
     "dev": "tsx src/index.ts",
+    "test": "tsx src/index.test.ts",
+    "test:watch": "tsx --watch-path=src src/index.test.ts",
     "typecheck": "tsc",
     "inspect": "mcp-inspector"
   },

exercises/01.start/01.problem/package.json

@@ -0,0 +1,81 @@
+import { test, beforeEach, afterEach } from 'node:test'
+import { invariant } from '@epic-web/invariant'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { StdioClientTransport } from '@modelcontextprotocol/sdk/client/stdio.js'
+import { z } from 'zod'
+
+let client: Client
+
+beforeEach(async () => {
+	client = new Client({
+		name: 'EpicMathTester',
+		version: '1.0.0',
+	})
+	const transport = new StdioClientTransport({
+		command: 'tsx',
+		args: ['src/index.ts'],
+	})
+	await client.connect(transport)
+})
+
+afterEach(async () => {
+	await client.transport?.close()
+})
+
+await test('Tool Definition', async (t) => {
+	const list = await client.listTools()
+	const [firstTool] = list.tools
+	invariant(firstTool, '🚨 No tools found')
+
+	const expectedToolFormatSchema = z.object({
+		name: z.string().regex(/^add$/i),
+		description: z.string().regex(/^add two numbers$/i),
+		inputSchema: z.object({
+			type: z.literal('object'),
+			properties: z.object({
+				firstNumber: z.object({
+					type: z.literal('number'),
+					description: z.string().regex(/first/i),
+				}),
+				secondNumber: z.object({
+					type: z.literal('number'),
+					description: z.string().regex(/second/i),
+				}),
+			}),
+		}),
+	})
+	assertSchema(expectedToolFormatSchema, firstTool)
+})
+
+await test('Tool Call', async (t) => {
+	const result = await client.callTool({
+		name: 'add',
+		arguments: {
+			firstNumber: 1,
+			secondNumber: 2,
+		},
+	})
+
+	assertSchema(
+		z.object({
+			content: z.array(
+				z.object({ type: z.literal('text'), text: z.string().regex(/3/) }),
+			),
+		}),
+		result,
+	)
+})
+
+// TODO: maybe there's a way within Zod to handle the error message so we can
+// just use parse and let it throw its own error.
+function assertSchema(
+	schema: z.ZodSchema,
+	value: unknown,
+): asserts value is z.infer<typeof schema> {
+	const result = schema.safeParse(value)
+	if (!result.success) {
+		console.error('🚨 The following value is invalid:')
+		console.dir(value, { depth: 8, colors: true })
+		throw result.error
+	}
+}

exercises/01.start/01.problem/src/index.test.ts

@@ -1,43 +1,29 @@
-import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
-import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
-import { DB } from './db'
-import { initializeTools } from './tools.ts'
+// 💰 you're gonna want these imports
+// import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+// import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js'
+// import { z } from 'zod'
 
-export class EpicMeMCP {
-	db: DB
-	server = new McpServer(
-		{
-			name: 'EpicMe',
-			version: '1.0.0',
-		},
-		{
-			capabilities: {
-				tools: {},
-			},
-			instructions: `
-EpicMe is a journaling app that allows users to write about and review their experiences, thoughts, and reflections.
+// 🐨 create a new McpServer
+// - it should have a name of 'EpicMath' and a version of '1.0.0'
+// - it should have a capabilities object with a tools property that is an empty object
+// - it should have instructions for the LLM to know what this server can be used to do
 
-These tools are the user's window into their journal. With these tools and your help, they can create, read, and manage their journal entries and associated tags.
+// 🐨 add a tool to the server with the server.tool API
+// - it should be named 'add'
+// - it should have a description explaining what it can be used to do
+// - provide an input schema object with two properties which are validated with zod (give them descriptions as well):
+//   - firstNumber: a number
+//   - secondNumber: a number
+// - it should return a standard text response with the sum of the two numbers
 
-You can also help users add tags to their entries and get all tags for an entry.
-			`.trim(),
-		},
-	)
+async function main() {
+	// 🐨 create a new StdioServerTransport
+	// 🐨 connect the server to the transport
 
-	constructor(path: string) {
-		this.db = DB.getInstance(path)
-	}
-	async init() {
-		await initializeTools(this)
-	}
-}
+	// 🐨 add a log (using console.error) to the console to let the user know the server is running
 
-async function main() {
-	const agent = new EpicMeMCP('./db.sqlite')
-	await agent.init()
-	const transport = new StdioServerTransport()
-	await agent.server.connect(transport)
-	console.error('EpicMe MCP Server running on stdio')
+	// 💣 you can delete this once you're done
+	throw new Error('Not implemented')
 }
 
 main().catch((error) => {

exercises/01.start/01.problem/src/index.ts

@@ -0,0 +1 @@
+# Start