require 'rails_helper'
require 'cache'

describe Gaps do

  it 'returns no gaps for empty data' do
    expect(Gaps.new(nil, nil)).to be_blank
  end

  it 'returns no gaps with one element' do
    expect(Gaps.new([1], [1])).to be_blank
  end

  it 'returns no gaps when all elements are present' do
    expect(Gaps.new([1, 2, 3], [1, 2, 3])).to be_blank
  end

  context "single element gap" do
    let(:gap) { Gaps.new([1, 3], [1, 2, 3]) }

    it 'has a gap for post 3' do
      expect(gap).not_to be_blank
      expect(gap.before[3]).to eq([2])
      expect(gap.after).to be_blank
    end
  end

  context "larger gap" do
    let(:gap) { Gaps.new([1, 2, 3, 6, 7], [1, 2, 3, 4, 5, 6, 7]) }

    it 'has a gap for post 6' do
      expect(gap).not_to be_blank
      expect(gap.before[6]).to eq([4, 5])
      expect(gap.after).to be_blank
    end
  end

  context "multiple gaps" do
    let(:gap) { Gaps.new([1, 5, 6, 7, 10], [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]) }

    it 'has both gaps' do
      expect(gap).not_to be_blank
      expect(gap.before[5]).to eq([2, 3, 4])
      expect(gap.before[10]).to eq([8, 9])
      expect(gap.after).to be_blank
    end
  end

  context "a gap in the beginning" do
    let(:gap) { Gaps.new([2, 3, 4], [1, 2, 3, 4]) }

    it 'has the gap' do
      expect(gap).not_to be_blank
      expect(gap.before[2]).to eq([1])
      expect(gap.after).to be_blank
    end
  end

  context "a gap in the ending" do
    let(:gap) { Gaps.new([1, 2, 3], [1, 2, 3, 4]) }

    it 'has the gap' do
      expect(gap).not_to be_blank
      expect(gap.before).to be_blank
      expect(gap.after[3]).to eq([4])
    end
  end

  context "a large gap in the ending" do
    let(:gap) { Gaps.new([1, 2, 3], [1, 2, 3, 4, 5, 6]) }

    it 'has the gap' do
      expect(gap).not_to be_blank
      expect(gap.before).to be_blank
      expect(gap.after[3]).to eq([4, 5, 6])
    end
  end

end