Rule proposal: avoid setup code outside of tests or hooks

[lo1tuma]

This should be considered a warning:

describe('foo',  function ()  {
    var fixture = fs.readFileSync('foo.txt');
});

You should read the file in a before hook instead.

The problem with such code is that it will be executed during the process startup time. It will be even executed if you skip the test suite.

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I'm not 100% sure how to achieve this. Disallowing every call expression would also disallow using forEach for parameterized tests.

[lo1tuma]

Fixed by #147