import { PassThrough } from "stream";
import { EventEmitter } from "events";
describe("mcpwrapped (CLI wrapper)", () => {
const originalArgv = process.argv.slice();
// Build a realistic fake child_process.spawn result.
function makeFakeChild() {
const child = new EventEmitter() as any;
child.stdout = new PassThrough();
child.stdin = new PassThrough();
// Prevent backing up stdio forever
child.stdin.write = jest.fn();
// Emit exit/close after stdout ends
child.stdout.on("end", () => {
if (!child.__closed) {
child.__closed = true;
child.emit("exit", 0);
child.emit("close", 0);
}
});
// Allow manual termination
child.kill = () => {
child.stdout.end();
child.stdin.end();
if (!child.__closed) {
child.__closed = true;
child.emit("exit", 0);
child.emit("close", 0);
}
};
return child;
}
afterEach(() => {
jest.restoreAllMocks();
jest.clearAllTimers();
jest.resetModules();
process.argv = originalArgv.slice();
});
test("exits with usage when no real command provided", () => {
const exitSpy = jest.spyOn(process, "exit").mockImplementation(((
code?: number,
) => {
throw new Error("exited:" + (code ?? 0));
}) as any);
const errSpy = jest.spyOn(console, "error").mockImplementation(() => {});
const { run } = require("../src/mcpwrapped");
expect(() => {
run([], new PassThrough(), new PassThrough());
}).toThrow("exited:1");
expect(exitSpy).toHaveBeenCalledWith(1);
expect(errSpy).toHaveBeenCalledWith(
"Usage: mcpwrapped --visible_tools=a,b realCmd realArgs...",
);
});
test("forwards non-JSON stdout lines unchanged", async () => {
const cp = require("child_process");
const child = makeFakeChild();
jest.spyOn(cp, "spawn").mockImplementation(() => child);
const { run } = require("../src/mcpwrapped");
const stdin = new PassThrough();
const stdout = new PassThrough();
const stdoutWrite = jest.fn();
stdout.write = stdoutWrite;
run(["--visible_tools=", "cmd"], stdin, stdout);
// Trigger message + child exit
child.stdout.end("hello\n");
// allow event loop to flush
await new Promise((resolve) => setImmediate(resolve));
expect(stdoutWrite).toHaveBeenCalledWith("hello\n");
});
test("filters capabilities.tools according to --visible_tools", async () => {
const cp = require("child_process");
const child = makeFakeChild();
jest.spyOn(cp, "spawn").mockImplementation(() => child);
const { run } = require("../src/mcpwrapped");
const stdin = new PassThrough();
const stdout = new PassThrough();
const stdoutWrite = jest.fn();
stdout.write = stdoutWrite;
run(["--visible_tools=a", "cmd"], stdin, stdout);
const msg = {
result: {
capabilities: {
tools: {
a: { description: "allowed" },
b: { description: "blocked" },
},
},
},
};
child.stdout.end(JSON.stringify(msg) + "\n");
await new Promise((resolve) => setImmediate(resolve));
expect(stdoutWrite).toHaveBeenCalledTimes(1);
const raw = stdoutWrite.mock.calls[0][0];
const str =
typeof raw === "string" ? raw : Buffer.from(raw as Uint8Array).toString();
const parsed = JSON.parse(str);
expect(parsed.result.capabilities.tools).toHaveProperty("a");
expect(parsed.result.capabilities.tools).not.toHaveProperty("b");
});
test("filters legacy msg.result.tools[] by name", async () => {
const cp = require("child_process");
const child = makeFakeChild();
jest.spyOn(cp, "spawn").mockImplementation(() => child);
const { run } = require("../src/mcpwrapped");
const stdin = new PassThrough();
const stdout = new PassThrough();
const stdoutWrite = jest.fn();
stdout.write = stdoutWrite;
run(["--visible_tools=a", "cmd"], stdin, stdout);
const msg = {
result: {
tools: [
{ name: "a", info: 1 },
{ name: "b", info: 2 },
],
},
};
child.stdout.end(JSON.stringify(msg) + "\n");
await new Promise((resolve) => setImmediate(resolve));
expect(stdoutWrite).toHaveBeenCalledTimes(1);
const raw = stdoutWrite.mock.calls[0][0];
const str =
typeof raw === "string" ? raw : Buffer.from(raw as Uint8Array).toString();
const parsed = JSON.parse(str);
expect(parsed.result.tools).toHaveLength(1);
expect(parsed.result.tools[0].name).toBe("a");
});
});
