1. Create [[ https://test.wikipedia.org/wiki/Talk:QUnit?debug=true | a wiki page with the following content ]] and save it:
```lang=html
<div id="qunit"></div>
<div id="qunit-fixture"></div>
```
2. Open browser's console and paste the following code into it:
```lang=javascript
mw.loader.using('jquery.qunit').done(function () {
QUnit.test( "one", function( assert ) {
assert.ok( 1 == "1", "Passed!" );
});
QUnit.test( "two", function( assert ) {
assert.ok( 2 == "2", "Passed!" );
});
QUnit.test( "three", function( assert ) {
assert.ok( 3 == "3", "Passed!" );
});
});
```
The test-runner will halt while "Running" the tests and won't finish.
The following warning is shown in Firefox's console:
```
performance.measure could not be executed because of An invalid or illegal string was specified
```
Strangely, if I delete any one of the three tests, then the other two will pass successfully.
3. But if I run the same tests by loading QUnit from their original site, e.i.:
```lang=javascript
jQuery.getScript('https://code.jquery.com/qunit/qunit-2.9.1.js').done(function () {
QUnit.test( "one", function( assert ) {
assert.ok( 1 == "1", "Passed!" );
});
QUnit.test( "two", function( assert ) {
assert.ok( 2 == "2", "Passed!" );
});
QUnit.test( "three", function( assert ) {
assert.ok( 3 == "3", "Passed!" );
});
});
$('<link/>', {
rel: 'stylesheet',
type: 'text/css',
href: 'https://code.jquery.com/qunit/qunit-2.9.1.css'
}).appendTo('head');
```
now all three tests pass successfully.
I'm not good with JavaScript, I might be doing something wrong, otherwise I'm suspicious that `mw.loader.using` is not loading the QUnit properly. I expect the code in step 2 to work the same way as loading the libraries from the original site (step 3).