# encoding: utf-8 require 'spec_helper' describe Function::Connective::Negation, '#inverse' do subject { object.inverse } let(:attribute) { Attribute::Integer.new(:id) } let(:operand) { attribute.eq(1) } let(:object) { described_class.new(operand) } it_should_behave_like 'an idempotent method' it 'returns the operand' do should be(operand) end it 'is not invertible' do subject.inverse.should_not eql(object) end end