BDD tests: provide more info if 'parameters were valid' fails

[jessitron]

My tests results include:

    | ├─┬ parameters were valid: Failed
    | | └── function (p, w) {
    | |         return w.invalidParameters() === null;
    | |     }

Let's make this console.log the contents of invalidParameters, please.

[jessitron]

I'd do it now but I don't have time to tweak or test it.