Testing when using window

windowFakeAndTesting.js

describe('myTest', function () {
    it('should interact with window', function () {
        function AudioContext() {
            this.foo = 'bar';
        }

        AudioContext.prototype = {
            doThatThingYouDo: sinon.spy()
        };

        const windowFake = {
            AudioContext: AudioContext
        };

        buildApi(windowFake);
        windowFake.exportedFunctions.callTheThing();

        assert.equal(AudioContext.prototype.doThatThingYouDo.callCount, 1);
    });
});


function buildApi(window) {

    function callTheThing() {
        const audioContext = new window.AudioContext();

        audioContext.doThatThingYouDo();
    }

    const exportedFunctions = {
        callTheThing: callTheThing
    }

    window.exportedFunctions = exportedFunctions;
}