'Check widget for dataset with no rows and for dataset with no attributes'

def test_empty_data(self):

    data = Table('iris')
    self.send_signal(self.widget.Inputs.data, data[:0])
    self.assertTrue(self.widget.Error.no_instances.is_shown())
    domain = Domain([], None, data.domain.variables)
    new_data = Table.from_table(domain, data)
    self.send_signal(self.widget.Inputs.data, new_data)
    self.assertTrue(self.widget.Error.no_features.is_shown())
    self.assertFalse(self.widget.Error.no_instances.is_shown())
    self.send_signal(self.widget.Inputs.data, None)
    self.assertFalse(self.widget.Error.no_features.is_shown())
