Global leaks old firefox versions strange behavior

[bgaillard]

Hi, i'm currently doing lot of tests using Browserstack.

Today I executed unit tests on the ~500 browsers Browserstack supports and encountered a strange Error: global leak detected: navigator which appears only with old Firefox versions (the error is encountered in Firefox 5.X and older).

My settings are very simple ;

<script type="text/javascript">
    mocha.setup({ui: 'bdd'});
</script>

<script type="text/javascript" src="test/spec/my-tests.js"></script>

<script type="text/javascript">
    mocha.checkLeaks();
    mocha.run();
</script>

The first time I execute the tests the following error is reported : Error: global leak detected: navigator.

But if I refresh the tab it works without problem, what's strange is that if I add only navigator.userAgent; before mocha.checkLeaks(); then it works.

...
<script type="text/javascript">
    navigator.userAgent;
    mocha.checkLeaks();
    mocha.run();
</script>

Do you know why I encounter this strange behavior ? Is it a bug in Mocha's leaks detection ?

If somebody else encounters the same error the workaround is simply to change you Mocha settings.

mocha.setup(
    {
        ui: 'bdd',
        globals: ['navigator'] 
    }
);

Thanks,

Baptiste

[boneskull]

if a new property appears in the global context between the mocha.run() and its completion, the global leak detection error will occur. what FF is doing, I don't know, but that's why. good to know for people using older FF versions though--thanks

[bgaillard]

Hi @boneskull, ok I understand now, makes sense.

So old FF versions should have a buggy page initialization.

Thanks for the explanations !