Jasmine spyOn NodeJS

Question

I was wondering if you can help me. I am using Jasmine spies with NodeJS. I am trying to mock a function, which gets called by another function. But the mock does not look like it is working.

api.js

function hello() {
    greeting();
}

function greeting() {
    console.log("welcome!");
    console.log("But instead it prints this!");
}

module.export = {
    hello    : hello,
    greeting : greeting
}

api-spec.js

const api = require("./api")

describe("testing jasmine spies", function() {
    it("mocks the greeting", function() => {
        spyOn(api, "greeting").and.callFake(function() {
            console.log("it should print this, since I am mocking it...")
        });

        api.hello();
    });
});

As you can see, I mock greeting, which gets called by hello. So, when I call hello from my spec, I expect it to call the mocked version of my greeting function. But it calls the actual implementation instead.

Can you please help me?

Answer 1

Please consider the difference how to test this.greeting() and greeting() function call.

Executed in global / window scope

function hello() {
  greeting();
}

function greeting() {
  console.log('original greeting')
}

api = {
  hello: hello,
  greeting: greeting
}

describe("jasmine spies on global object", function() {
  it("mocks the window.greeting()", function() {
    spyOn(window, "greeting").and.callFake(function() {
      console.log("stubbed `api.greeting()`")
    });
    api.hello();
    expect(window.greeting).toHaveBeenCalled();
  });
});

<link href="//safjanowski.github.io/jasmine-jsfiddle-pack/pack/jasmine.css" rel="stylesheet" />
<script src="//safjanowski.github.io/jasmine-jsfiddle-pack/pack/jasmine-2.0.3-concated.js"></script>

Executed in object context

function hello() {
  this.greeting();
}

function greeting() {
  console.log('original greeting')
}

api = {
  hello: hello,
  greeting: greeting
}

describe("jasmine spies on object", function() {
  it("mocks the api.greeting()", function() {
    spyOn(api, "greeting").and.callFake(function() {
      console.log("stubbed `api.greeting()`")
    });
    api.hello();
    expect(api.greeting).toHaveBeenCalled();
  });
});

<link href="//safjanowski.github.io/jasmine-jsfiddle-pack/pack/jasmine.css" rel="stylesheet" />
<script src="//safjanowski.github.io/jasmine-jsfiddle-pack/pack/jasmine-2.0.3-concated.js"></script>