'Test metadata_field_keys property.'

def test_metadata_keys(self):

    form = NewQuestionForm()
    expected = ['useragent']
    actual = form.metadata_field_keys
    eq_(expected, actual)
    product = {'key': 'desktop', 'name': 'Firefox    on    desktop', 'extra_fields': ['troubleshooting', 'ff_version', 'os', 'plugins']}
    form = NewQuestionForm(product=product)
    expected = ['troubleshooting', 'ff_version', 'os', 'plugins', 'useragent']
    actual = form.metadata_field_keys
    eq_(expected, actual)
    category = {'key': 'd6', 'name': 'I    have    another    kind    of    problem    with    Firefox', 'extra_fields': ['frequency', 'started']}
    form = NewQuestionForm(product=product, category=category)
    expected = ['frequency', 'started', 'troubleshooting', 'ff_version', 'os', 'plugins', 'useragent']
    actual = form.metadata_field_keys
    eq_(expected, actual)
