Development with Python

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3. I’ve called this object a “mock”, but it’s probably more correctly called a “spy”. We don’t have to concern
ourselves with the differences in this book, but for more on the general class of tools called “Test Doubles”,
including the difference between stubs, mocks, fakes, and spies, see by Emily Bache.
<script src= "></script>
<script src="../../../superlists/static/tests/qunit.js"></script>
<script src="../accounts.js"></script>
<script>
/*global $, test, equal, sinon, Superlists */
test("initialize binds sign in button to navigator.id.request", function () {
var requestWasCalled = false; //
var mockRequestFunction = function () { requestWasCalled = true; }; //
var mockNavigator = { //
id: {
request: mockRequestFunction
}
};
Superlists.Accounts.initialize(mockNavigator); //
$('#id_login').trigger('click'); //
equal(requestWasCalled, true); //
});
</script>
One of the best ways to understand this test, or indeed any test, is to work backwards.
The first thing we see is the assertion:
We are asserting that a variable called requestWasCalled is true. We’re checking
that, one way or another, the request function, as in navigator.id.request,
was called.
Called when? When a click event happens to the id_login element.
Before we trigger that click event, we call our Superlists.Accounts.initial
ize function, just like we will on the real page. The only difference is, instead of
passing it the real global navigator object from Persona, we pass in a fake one
called mockNavigator .3
That’s defined as a generic JavaScript object, with an attribute called id which
in turn has an attribute called request, which we’re assigning to a variable called
mockRequestFunction .
mockRequestFunction we define as a very simple function, which if called will
simply set the value of the requestWasCalled variable to true.
And finally (firstly?) we make sure that requestWasCalled starts out as false.
JavaScript Unit Tests Involving External Components: Our First Mocks! | 259