@featurevisor/sdk/src/emitter.spec.ts

Featurevisor SDK for Node.js and the browser

import { Emitter, EventDetails } from "./emitter";

describe("Emitter", () => {
  let emitter: Emitter;
  let handledDetails: EventDetails[] = [];

  function handleDetails(details: EventDetails) {
    handledDetails.push(details);
  }

  beforeEach(() => {
    emitter = new Emitter();
    handledDetails = [];
  });

  it("should add a listener for an event", function () {
    const unsubscribe = emitter.on("datafile_set", handleDetails);

    expect(emitter.listeners["datafile_set"]).toContain(handleDetails);
    expect(emitter.listeners["datafile_changed"]).toBeUndefined();
    expect(emitter.listeners["context_set"]).toBeUndefined();
    expect(emitter.listeners["datafile_set"].length).toBe(1);

    // trigger already subscribed event
    emitter.trigger("datafile_set", { key: "value" });
    expect(handledDetails.length).toBe(1);
    expect(handledDetails[0]).toEqual({ key: "value" });

    // trigger unsubscribed event
    emitter.trigger("sticky_set", { key: "value2" });
    expect(handledDetails.length).toBe(1);

    // unsubscribe
    unsubscribe();
    expect(emitter.listeners["datafile_set"].length).toBe(0);

    // clear all
    emitter.clearAll();
    expect(emitter.listeners).toEqual({});
  });
});