mocking window.location.href in Javascript

Solution 1:

The best way to do this is to create a helper function somewhere and then mock that:

 var mynamespace = mynamespace || {};
    mynamespace.util = (function() {
      function getWindowLocationHRef() {
          return window.location.href;
      }
      return { 
        getWindowLocationHRef: getWindowLocationHRef
      }
    })();

Now instead of using window.location.href directly in your code simply use this instead. Then you can replace this method whenever you need to return a mocked value:

mynamespace.util.getWindowLocationHRef = function() {
  return "http://mockhost/mockingpath" 
};

If you want a specific part of the window location such as a query string parameter then create helper methods for that too and keep the parsing out of your main code. Some frameworks such as jasmine have test spies that can not only mock the function to return desired values, but can also verified it was called:

spyOn(mynamespace.util, 'getQueryStringParameterByName').andReturn("desc");
//...
expect(mynamespace.util.getQueryStringParameterByName).toHaveBeenCalledWith("sort");

Solution 2:

I would propose two solutions which have already been hinted at in previous posts here:

• Create a function around the access, use that in your production code, and stub this with Jasmine in your tests:

  var actions = {
      getCurrentURL: function () {
          return window.location.href;
      },
      paramToVar: function (testData) {
          ...
          var url = getCurrentURL();
          ...
      }
  };
  // Test
  var urlSpy = spyOn(actions, "getCurrentURL").andReturn("http://my/fake?param");
  expect(actions.paramToVar(test_Data)).toEqual("bar");
  

• Use a dependency injection and inject a fake in your test:

  var _actions = function (window) {
      return {
          paramToVar: function (testData) {
              ...
              var url = window.location.href;
              ...
          }
      };
  };
  var actions = _actions(window);
  // Test
  var fakeWindow = {
     location: { href: "http://my/fake?param" }
  };
  var fakeActions = _actions(fakeWindow);
  expect(fakeActions.paramToVar(test_Data)).toEqual("bar");
  

Solution 3:

You need to simulate local context and create your own version of window and window.location objects

var localContext = {
    "window":{
        location:{
            href: "http://www.website.com?varName=foo"
        }
    }
}

// simulated context
with(localContext){
    console.log(window.location.href);
    // http://www.website.com?varName=foo
}

//actual context
console.log(window.location.href);
// http://www.actual.page.url/...

If you use with then all variables (including window!) will firstly be looked from the context object and if not present then from the actual context.

Solution 4:

Sometimes you may have a library that modifies window.location and you want to allow for it to function normally but also be tested. If this is the case, you can use a closure to pass your desired reference to your library such as this.

/* in mylib.js */
(function(view){
    view.location.href = "foo";
}(self || window));

Then in your test, before including your library, you can redefine self globally, and the library will use the mock self as the view.

var self = {
   location: { href: location.href }
};

In your library, you can also do something like the following, so you may redefine self at any point in the test:

/* in mylib.js */
var mylib = (function(href) {
    function go ( href ) {
       var view = self || window;
       view.location.href = href;
    }
    return {go: go}
}());

In most if not all modern browsers, self is already a reference to window by default. In platforms that implement the Worker API, within a Worker self is a reference to the global scope. In node.js both self and window are not defined, so if you want you can also do this:

self || window || global

This may change if node.js really does implement the Worker API.