Using Jasmine spyOn to mock function in Browserify module

Question

I'm trying to run a unit test on a function (testFunc). testFunc calls another function (secondFunc) which I would like to mock. Can I mock secondFunc so that when it is called in the context of testFunc, the spiedOn version of secondFunc is called? If not, how should I reformat my browserify module to make it testable?

Currently the setup looks something like this:

app.js (Browserify Module)

module.exports = (function () {
    function testFunc() {
        secondFunc();
    }

    function secondFunc(){
        console.log('not mocked!');
    }

    return {
        testFunc, secondFunc
    };

})();

test.js (Jasmine Test)

describe("testFunc", () => {
    let app = require('./app');

    beforeEach(() => {
        spyOn(app, 'secondFunc');
    });

    it("should call secondFunc spy", () => {
        app.testFunc();
        expect(app.secondFunc).toHaveBeenCalled();
    });

});

Answer 1

The way you have it now, the spyOn is replacing the secondFunc property on your returned object with a proxy, but your code calls the secondFunc function that is inside the closure of the anonymous function. There are several ways to restructure your code to better expose the functions.

You could structure your module this way:

exports.testFunc = function() {
    exports.secondFunc();
}

exports.secondFunc = function(){
    console.log('not mocked!');
}

which is a lot smaller, easier to read, and let you mock the secondFunc function.