Karma not load a function

I want test a function using Karma: This is the structure of my code:

WebContent
|
|___js
|   |
|   |__sourceCode.js
|
|___test-resources
    |
    |__myTest.js

This is the full content of sourceCode.js :

ui5bp.sourceCode={
    doubleSum:function (a, b) {
        return (a + b) * 2;
    }
}

/*
function doubleSum(a, b) {
    return (a + b) * 2;
}*/

and this an extract of my karma config file:

...
files: [
      'WebContent/test-resources/sourceCode.js',
      //'WebContent/test-resources/myTest.js'
    ],
...

Ok. Now I want run Karma, at the moment without test (in the config file I have commented the test) but I have a problem:

ui5bp is not defined

instead if I modify sourceCode writing directly the function, I don't have problems!

I have organized my code using objects grouping functions and I would like test these funcions by init tests.