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import { describe, expect, it } from "vitest";
import { McpClient } from "./client.js";
import type { Connection } from "./transport.js";
function makeMockConnection(): Connection & {
responses: Map<string, unknown>;
feedResponse: (method: string, result: unknown) => void;
notifications: Array<{ method: string; params: unknown }>;
} {
const responses = new Map<string, unknown>();
const pendingRequests = new Map<number, { method: string; resolve: (v: unknown) => void }>();
let nextId = 1;
const notifications: Array<{ method: string; params: unknown }> = [];
const notificationHandlers = new Map<string, (params: unknown) => void>();
return {
responses,
notifications,
feedResponse: (_method: string, _result: unknown) => {},
send: (method: string, _params?: unknown) => {
const id = nextId++;
return new Promise((resolve) => {
pendingRequests.set(id, { method, resolve });
// Auto-respond for initialize
if (method === "initialize") {
resolve({
protocolVersion: "2025-11-25",
capabilities: { tools: { listChanged: true } },
serverInfo: { name: "test-server", version: "1.0.0" },
});
} else if (method === "tools/list") {
resolve({
tools: [
{
name: "test_tool",
description: "A test tool",
inputSchema: { type: "object", properties: { input: { type: "string" } } },
},
],
});
} else if (method === "tools/call") {
resolve({
content: [{ type: "text", text: "result from tool" }],
isError: false,
});
}
});
},
notify: (method: string, params?: unknown) => {
notifications.push({ method, params });
},
onNotification: (method: string, handler: (params: unknown) => void) => {
notificationHandlers.set(method, handler);
},
close: () => {},
pid: 999,
};
}
describe("McpClient", () => {
it("initialize sends correct protocolVersion + capabilities", async () => {
const conn = makeMockConnection();
const client = new McpClient({ connection: conn });
const result = await client.initialize();
expect(result.protocolVersion).toBe("2025-11-25");
expect(result.capabilities.tools?.listChanged).toBe(true);
expect(result.serverInfo.name).toBe("test-server");
expect(client.getState()).toBe("connected");
// Should have sent notifications/initialized
expect(conn.notifications.length).toBe(1);
expect(conn.notifications[0].method).toBe("notifications/initialized");
});
it("listTools returns parsed tools", async () => {
const conn = makeMockConnection();
const client = new McpClient({ connection: conn });
await client.initialize();
const tools = await client.listTools();
expect(tools.length).toBe(1);
expect(tools[0].name).toBe("test_tool");
expect(tools[0].description).toBe("A test tool");
});
it("callTool sends name + arguments", async () => {
const conn = makeMockConnection();
let callParams: unknown = null;
const origSend = conn.send.bind(conn);
conn.send = (method: string, params?: unknown) => {
if (method === "tools/call") callParams = params;
return origSend(method, params);
};
const client = new McpClient({ connection: conn });
await client.initialize();
const result = await client.callTool("test_tool", { input: "hello" });
expect(callParams).toEqual({ name: "test_tool", arguments: { input: "hello" } });
expect(result.content).toEqual([{ type: "text", text: "result from tool" }]);
expect(result.isError).toBe(false);
});
it("list_changed triggers re-list", async () => {
const conn = makeMockConnection();
const notificationHandlers = new Map<string, (params: unknown) => void>();
conn.onNotification = (method: string, handler: (params: unknown) => void) => {
notificationHandlers.set(method, handler);
};
const client = new McpClient({ connection: conn });
let toolsChangedFired = false;
client.onToolsChanged(() => {
toolsChangedFired = true;
});
await client.initialize();
// Simulate list_changed notification
const handler = notificationHandlers.get("notifications/tools/list_changed");
expect(handler).toBeDefined();
handler?.(undefined);
expect(toolsChangedFired).toBe(true);
});
it("handles server error on initialize", async () => {
const conn = makeMockConnection();
conn.send = (method: string) => {
if (method === "initialize") {
return Promise.reject(new Error("Server startup failed"));
}
return Promise.resolve({});
};
const client = new McpClient({ connection: conn });
await expect(client.initialize()).rejects.toThrow("Server startup failed");
expect(client.getState()).toBe("error");
});
it("callTool rejects when not connected", async () => {
const conn = makeMockConnection();
const client = new McpClient({ connection: conn });
await expect(client.callTool("test", {})).rejects.toThrow("Client not connected");
});
it("listTools rejects when not connected", async () => {
const conn = makeMockConnection();
const client = new McpClient({ connection: conn });
await expect(client.listTools()).rejects.toThrow("Client not connected");
});
it("close sets state to disconnected", async () => {
const conn = makeMockConnection();
const client = new McpClient({ connection: conn });
await client.initialize();
expect(client.getState()).toBe("connected");
client.close();
expect(client.getState()).toBe("disconnected");
});
it("callTool with abort signal", async () => {
const conn = makeMockConnection();
let resolveRequest: ((v: unknown) => void) | null = null;
conn.send = (method: string) => {
if (method === "tools/call") {
return new Promise((resolve) => {
resolveRequest = resolve;
});
}
if (method === "initialize") {
return Promise.resolve({
protocolVersion: "2025-11-25",
capabilities: {},
serverInfo: { name: "test", version: "1.0.0" },
});
}
return Promise.resolve({});
};
const client = new McpClient({ connection: conn });
await client.initialize();
const controller = new AbortController();
const callPromise = client.callTool("test", {}, controller.signal);
controller.abort();
await expect(callPromise).rejects.toThrow("Aborted");
// Clean up
resolveRequest?.({
content: [{ type: "text", text: "too late" }],
});
});
});
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