Negator Play

gistfile1.rb

require 'rspec'

module Negator
  def negate(method_name, as:)
    if instance_methods.include?(method_name)
      define_method(as) do
        !send(method_name)
      end
    end

    if singleton_methods.include?(method_name)
      define_singleton_method (as) do
        !send(method_name)
      end
    end
  end
end


class InstanceMethodTester
  extend Negator
  def verified; true; end
  negate :verified, as: :unverified
end

class ClassMethodTester
  extend Negator
  def self.verified; true; end
  negate :verified, as: :unverified
end

class MixedTester
  extend Negator
  def self.verified; true; end
  def verified; true; end
  negate :verified, as: :unverified
end

RSpec.describe "negator" do
  context 'instance method' do
    it 'negates to falsy' do
      expect(InstanceMethodTester.new.unverified).to eql(false)
    end

    it 'responds to new method signature' do
      expect(InstanceMethodTester.new.respond_to?(:unverified)).to eql(true)
    end

    it 'does not respond to class method' do
      expect(InstanceMethodTester.respond_to?(:unverified)).to eql(false)
    end
  end

  context 'class method' do
    it 'negates to falsy' do
      expect(ClassMethodTester.unverified).to eql(false)
    end

    it 'responds to new method signature' do
      expect(ClassMethodTester.respond_to?(:unverified)).to eql(true)
    end

    it 'does not respond to instance method' do
      expect(ClassMethodTester.new.respond_to?(:unverified)).to eql(false)
    end
  end

  context 'mixed method' do
    it 'negates class method' do
      expect(MixedTester.unverified).to eql(false)
    end

    it 'negates instance method' do
      expect(MixedTester.new.unverified).to eql(false)
    end

    it 'negated class method responds to new method signature' do
      expect(MixedTester.new.respond_to?(:unverified)).to eql(true)
    end

    it 'negated instance method responds to new method signature' do
      expect(MixedTester.respond_to?(:unverified)).to eql(true)
    end
  end
end