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| 1 | +import { InMemoryTransport, type JSONRPCMessage, SdkError, SdkErrorCode } from '@modelcontextprotocol/core'; |
| 2 | +import { describe, expect, test } from 'vitest'; |
| 3 | +import * as z from 'zod/v4'; |
| 4 | + |
| 5 | +import { Client } from '../../src/client/client.js'; |
| 6 | + |
| 7 | +/** |
| 8 | + * These tests exercise the `Client.extension()` factory and the client side of the |
| 9 | + * `capabilities.extensions` round-trip via `initialize`. The `ExtensionHandle` class itself is |
| 10 | + * unit-tested in `@modelcontextprotocol/core/test/shared/extensionHandle.test.ts`. |
| 11 | + */ |
| 12 | + |
| 13 | +interface RawServerHarness { |
| 14 | + serverSide: InMemoryTransport; |
| 15 | + capturedInitParams: Promise<Record<string, unknown>>; |
| 16 | +} |
| 17 | + |
| 18 | +function rawServer(serverCapabilities: Record<string, unknown> = {}): RawServerHarness { |
| 19 | + const [clientSide, serverSide] = InMemoryTransport.createLinkedPair(); |
| 20 | + let resolveInit: (p: Record<string, unknown>) => void; |
| 21 | + const capturedInitParams = new Promise<Record<string, unknown>>(r => { |
| 22 | + resolveInit = r; |
| 23 | + }); |
| 24 | + serverSide.onmessage = (msg: JSONRPCMessage) => { |
| 25 | + if ('method' in msg && msg.method === 'initialize' && 'id' in msg) { |
| 26 | + resolveInit((msg.params ?? {}) as Record<string, unknown>); |
| 27 | + void serverSide.send({ |
| 28 | + jsonrpc: '2.0', |
| 29 | + id: msg.id, |
| 30 | + result: { |
| 31 | + protocolVersion: '2025-11-25', |
| 32 | + capabilities: serverCapabilities, |
| 33 | + serverInfo: { name: 'raw-server', version: '0.0.0' } |
| 34 | + } |
| 35 | + }); |
| 36 | + } |
| 37 | + }; |
| 38 | + void serverSide.start(); |
| 39 | + // Expose clientSide via the harness's serverSide.peer for the test to connect to. |
| 40 | + return { serverSide: clientSide, capturedInitParams }; |
| 41 | +} |
| 42 | + |
| 43 | +describe('Client.extension()', () => { |
| 44 | + test('merges settings into capabilities.extensions and advertises them in initialize request', async () => { |
| 45 | + const client = new Client({ name: 'c', version: '1.0.0' }, { capabilities: {} }); |
| 46 | + client.extension('io.example/ui', { contentTypes: ['text/html'] }); |
| 47 | + client.extension('com.acme/widgets', { v: 2 }); |
| 48 | + |
| 49 | + const harness = rawServer(); |
| 50 | + await client.connect(harness.serverSide); |
| 51 | + const initParams = await harness.capturedInitParams; |
| 52 | + |
| 53 | + const caps = initParams.capabilities as Record<string, unknown>; |
| 54 | + expect(caps.extensions).toEqual({ |
| 55 | + 'io.example/ui': { contentTypes: ['text/html'] }, |
| 56 | + 'com.acme/widgets': { v: 2 } |
| 57 | + }); |
| 58 | + }); |
| 59 | + |
| 60 | + test('throws AlreadyConnected after connect()', async () => { |
| 61 | + const client = new Client({ name: 'c', version: '1.0.0' }); |
| 62 | + const harness = rawServer(); |
| 63 | + await client.connect(harness.serverSide); |
| 64 | + |
| 65 | + expect(() => client.extension('io.example/ui', {})).toThrow(SdkError); |
| 66 | + try { |
| 67 | + client.extension('io.example/ui', {}); |
| 68 | + expect.fail('should have thrown'); |
| 69 | + } catch (e) { |
| 70 | + expect(e).toBeInstanceOf(SdkError); |
| 71 | + expect((e as SdkError).code).toBe(SdkErrorCode.AlreadyConnected); |
| 72 | + } |
| 73 | + }); |
| 74 | + |
| 75 | + test('throws on duplicate extension id', () => { |
| 76 | + const client = new Client({ name: 'c', version: '1.0.0' }); |
| 77 | + client.extension('io.example/ui', { v: 1 }); |
| 78 | + expect(() => client.extension('io.example/ui', { v: 2 })).toThrow(/already registered/); |
| 79 | + expect(() => client.extension('com.other/thing', {})).not.toThrow(); |
| 80 | + }); |
| 81 | + |
| 82 | + test("getPeerSettings() reads the server's capabilities.extensions[id] from initialize result", async () => { |
| 83 | + const PeerSchema = z.object({ availableDisplayModes: z.array(z.string()) }); |
| 84 | + const client = new Client({ name: 'c', version: '1.0.0' }); |
| 85 | + const handle = client.extension('io.example/ui', { clientSide: true }, { peerSchema: PeerSchema }); |
| 86 | + |
| 87 | + expect(handle.getPeerSettings()).toBeUndefined(); |
| 88 | + |
| 89 | + const harness = rawServer({ |
| 90 | + extensions: { 'io.example/ui': { availableDisplayModes: ['inline', 'fullscreen'] } } |
| 91 | + }); |
| 92 | + await client.connect(harness.serverSide); |
| 93 | + |
| 94 | + expect(handle.getPeerSettings()).toEqual({ availableDisplayModes: ['inline', 'fullscreen'] }); |
| 95 | + }); |
| 96 | + |
| 97 | + test('getPeerSettings() reflects reconnect to a different server', async () => { |
| 98 | + const client = new Client({ name: 'c', version: '1.0.0' }); |
| 99 | + const handle = client.extension('io.example/ui', {}); |
| 100 | + |
| 101 | + const harnessA = rawServer({ extensions: { 'io.example/ui': { v: 1 } } }); |
| 102 | + await client.connect(harnessA.serverSide); |
| 103 | + expect(handle.getPeerSettings()).toEqual({ v: 1 }); |
| 104 | + |
| 105 | + await client.close(); |
| 106 | + |
| 107 | + const harnessB = rawServer({ extensions: { 'io.example/ui': { v: 2 } } }); |
| 108 | + await client.connect(harnessB.serverSide); |
| 109 | + expect(handle.getPeerSettings()).toEqual({ v: 2 }); |
| 110 | + }); |
| 111 | +}); |
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