我如何覆盖javascript代码模式|| {}

Question

I am using JSCover running my Jasmine SpecRunner, which inspects a code fragment of the sort:

var MyRootObject = MyRootObject || {};

My goal is to bring coverage up to 100%, but I am not sure how best to cover this method of initialising the MyRootObject.

This pattern is used at the start of every library javascript file, to ensure that the order in which the files are loaded is unimportant (and the functions and variables inside are $.extend'ed).

The problem basically is that the first and only time this script is loaded in the SpecRunner, it runs only one side of this test, leaving the other path untested.

Answer 1

After digging around, I found a solution that works for me, of course, your mileage may vary:

var MyRootObject = MyRootObject || {};
$.extend(true, MyRootObject, {...});

I have replaced with:

var MyRootObject = $.extend(true, MyRootObject, {...});

Internally inside JQuery, if the target (MyRootObject) is null or undefined, it automatically assigns the target inside the function to be {}. By using an external library (which I was already using), I no longer have a conditional path I am not following, as this is delegated to the JQuery library.