memoizeLast.spec.js

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/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at <http://mozilla.org/MPL/2.0/>. */

import { memoizeLast } from "../memoizeLast";

const a = { number: 3 };

const b = { number: 4 };

function add(...numberObjects) {

  return numberObjects.reduce((prev, cur) => prev + cur.number, 0);

describe("memozie", () => {

  it("should re-calculate when a value changes", () => {

    const mAdd = memoizeLast(add);

    mAdd(a);

    expect(mAdd(a)).toEqual(3);

    mAdd(b);

    expect(mAdd(b)).toEqual(4);

});

  it("should only run once", () => {

    const mockAdd = jest.fn(add);

    const mAdd = memoizeLast(mockAdd);

    mAdd(a);

    mAdd(a);

    expect(mockAdd.mock.calls[0]).toEqual([{ number: 3 }]);

});

});