drawio-mcp-server/build/emitter_bus.test.js

Provides Draw.io services to MCP Clients

import { describe, it, expect, jest } from "@jest/globals";
import { EventEmitter } from "node:events";
import { create_bus } from "./emitter_bus.js";
import { bus_request_stream, bus_reply_stream } from "./types.js";
import { create_logger } from "./standard_console_logger.js";
describe("create_bus", () => {
    let emitter;
    let bus;
    const log = create_logger();
    beforeEach(() => {
        emitter = new EventEmitter();
        bus = create_bus(log)(emitter);
    });
    it("should send requests to extension via emitter", () => {
        const mockRequest = { type: "test_request", data: "test" };
        const emitSpy = jest.spyOn(emitter, "emit");
        bus.send_to_extension(mockRequest);
        expect(emitSpy).toHaveBeenCalledWith(bus_request_stream, mockRequest);
    });
    it("should register reply handlers and call them when matching events arrive", () => {
        const mockReply1 = jest.fn();
        const mockReply2 = jest.fn();
        const eventName1 = "event1";
        const eventName2 = "event2";
        const matchingEvent1 = { __event: eventName1, data: "test1" };
        const matchingEvent2 = { __event: eventName2, data: "test2" };
        const nonMatchingEvent = { __event: "other_event", data: "test3" };
        bus.on_reply_from_extension(eventName1, mockReply1);
        bus.on_reply_from_extension(eventName2, mockReply2);
        emitter.emit(bus_reply_stream, matchingEvent1);
        emitter.emit(bus_reply_stream, matchingEvent2);
        emitter.emit(bus_reply_stream, nonMatchingEvent);
        expect(mockReply1).toHaveBeenCalledWith(matchingEvent1);
        expect(mockReply2).toHaveBeenCalledWith(matchingEvent2);
        expect(mockReply1).not.toHaveBeenCalledWith(nonMatchingEvent);
        expect(mockReply2).not.toHaveBeenCalledWith(nonMatchingEvent);
    });
    it("should track all registered listeners", () => {
        // This test assumes the listeners array is accessible or there's a way to verify listeners
        // Since the original code doesn't expose the listeners array, we'll test indirectly
        const mockReply1 = jest.fn();
        const mockReply2 = jest.fn();
        bus.on_reply_from_extension("event1", mockReply1);
        bus.on_reply_from_extension("event2", mockReply2);
        // Verify listeners are working by emitting events
        const event1 = { __event: "event1", data: "test" };
        const event2 = { __event: "event2", data: "test" };
        emitter.emit(bus_reply_stream, event1);
        emitter.emit(bus_reply_stream, event2);
        expect(mockReply1).toHaveBeenCalledWith(event1);
        expect(mockReply2).toHaveBeenCalledWith(event2);
    });
    it("should only call the correct reply handler for each event", () => {
        const mockReply1 = jest.fn();
        const mockReply2 = jest.fn();
        const eventName1 = "event1";
        const eventName2 = "event2";
        const matchingEvent = { __event: eventName1, data: "test" };
        bus.on_reply_from_extension(eventName1, mockReply1);
        bus.on_reply_from_extension(eventName2, mockReply2);
        emitter.emit(bus_reply_stream, matchingEvent);
        expect(mockReply1).toHaveBeenCalledWith(matchingEvent);
        expect(mockReply2).not.toHaveBeenCalled();
    });
});