# frozen_string_literal: true

require "spec/spec_helper"

RSpec.describe Equatable, "#include" do
  let(:name)   { "Value" }
  let(:object) { described_class }

  context "without attributes" do
    let(:klass) { ::Class.new }

    subject { klass.new }

    before {
      allow(klass).to receive(:name).and_return(name)
      klass.send(:include, object)
    }

    it { is_expected.to respond_to(:compare?) }

    it { is_expected.to be_instance_of(klass) }

    it "has no attribute names" do
      expect(klass.comparison_attrs).to eq([])
    end

    describe "#inspect" do
      it { expect(subject.inspect).to eql("#<Value>") }
    end

    describe "#hash" do
      it { expect(subject.hash).to eql([klass].hash) }
    end

    describe "#eql?" do
      context "when objects are similar" do
        let(:other) { subject.dup }

        it { expect(subject.eql?(other)).to eql(true) }
      end

      context "when objects are different" do
        let(:other) { double("other") }

        it { expect(subject.eql?(other)).to eql(false) }
      end
    end

    describe "#==" do
      context "when objects are similar" do
        let(:other) { subject.dup }

        it { expect(subject == other).to eql(true) }
      end

      context "when objects are different" do
        let(:other) { double("other") }

        it { expect(subject == other).to eql(false) }
      end
    end

    context "equivalence relation" do
      let(:other)   { subject.dup }
      let(:another) { other.dup }

      it "is not equal to nil reference" do
        expect(subject.eql?(nil)).to eql(false)
      end

      it "is reflexive" do
        expect(subject.eql?(subject)).to eql(true)
      end

      it "is symmetric" do
        expect(subject.eql?(other)).to eql(other.eql?(subject))
      end

      it "is transitive" do
        expect(subject.eql?(other) && other.eql?(another))
          .to eql(subject.eql?(another))
      end
    end
  end

  context "with attributes" do
    let(:value) { 11 }
    let(:klass) {
      ::Class.new do
        include Equatable

        attr_reader :value

        def initialize(value)
          @value = value
        end
      end
    }

    before { allow(klass).to receive(:name).and_return(name) }

    subject { klass.new(value) }

    it "dynamically defines #hash method" do
      expect(klass.method_defined?(:hash)).to eql(true)
    end

    it "dynamically defines #inspect method" do
      expect(klass.method_defined?(:inspect)).to eql(true)
    end

    it { is_expected.to respond_to(:compare?) }

    it { is_expected.to respond_to(:eql?) }

    it "has comparison attribute names" do
      expect(klass.comparison_attrs).to eq([:value])
    end

    describe "#eql?" do
      context "when objects are similar" do
        let(:other) { subject.dup }

        it { expect(subject.eql?(other)).to eql(true) }
      end

      context "when objects are different" do
        let(:other) { double("other") }

        it { expect(subject.eql?(other)).to eql(false) }
      end
    end

    describe "#==" do
      context "when objects are similar" do
        let(:other) { subject.dup }

        it { expect(subject == other).to eql(true) }
      end

      context "when objects are different" do
        let(:other) { double("other") }

        it { expect(subject == other).to eql(false) }
      end
    end

    describe "#inspect" do
      it { expect(subject.inspect).to eql("#<Value value=11>") }
    end

    describe "#hash" do
      it { expect(subject.hash).to eql(([klass] + [value]).hash) }
    end

    context "equivalence relation" do
      let(:other)   { subject.dup }
      let(:another) { other.dup }

      it "is not equal to nil reference" do
        expect(subject.eql?(nil)).to eql(false)
      end

      it "is reflexive" do
        expect(subject.eql?(subject)).to eql(true)
      end

      it "is symmetric" do
        expect(subject.eql?(other)).to eql(other.eql?(subject))
      end

      it "is transitive" do
        expect(subject.eql?(other) && other.eql?(another))
          .to eql(subject.eql?(another))
      end
    end
  end
end