discourse/spec/lib/onpdiff_spec.rb

# frozen_string_literal: true

RSpec.describe ONPDiff do
  describe "diff" do
    it "returns an empty array when there is no content to diff" do
      expect(ONPDiff.new("", "").diff).to eq([])
    end

    it "returns an array with the operation code for each element" do
      expect(ONPDiff.new("abcd", "abef").diff).to eq(
        [["a", :common], ["b", :common], ["e", :add], ["f", :add], ["c", :delete], ["d", :delete]],
      )
    end

    it "bails out on large diffs" do
      a = SecureRandom.alphanumeric(5_000)
      b = SecureRandom.alphanumeric(5_000)
      expect(ONPDiff.new(a, b).diff).to eq([])
    end
  end

  describe "short_diff" do
    it "returns an empty array when there is no content to diff" do
      expect(ONPDiff.new("", "").short_diff).to eq([])
    end

    it "returns an array with the operation code for each element" do
      expect(ONPDiff.new("abc", "acd").short_diff).to eq(
        [["a", :common], ["b", :delete], ["c", :common], ["d", :add]],
      )
    end

    it "returns an array with sequentially similar operations merged" do
      expect(ONPDiff.new("abcd", "abef").short_diff).to eq(
        [["ab", :common], ["ef", :add], ["cd", :delete]],
      )
    end
  end

  describe "paragraph_diff" do
    it "returns an empty array when there is no content to diff" do
      expect(ONPDiff.new("", "").paragraph_diff).to eq([])
    end

    it "returns an array with the operation code for each element" do
      expect(ONPDiff.new("abc", "acd").paragraph_diff).to eq(
        [["a", :common], ["b", :delete], ["c", :common], ["d", :add]],
      )
    end

    it "pairs as many elements as possible" do
      expect(ONPDiff.new("abcd", "abef").paragraph_diff).to eq(
        [["a", :common], ["b", :common], ["e", :add], ["c", :delete], ["f", :add], ["d", :delete]],
      )

      expect(ONPDiff.new("abcde", "abfg").paragraph_diff).to eq(
        [
          ["a", :common],
          ["b", :common],
          ["c", :delete],
          ["d", :delete],
          ["f", :add],
          ["e", :delete],
          ["g", :add],
        ],
      )

      expect(ONPDiff.new("abcd", "abefg").paragraph_diff).to eq(
        [
          ["a", :common],
          ["b", :common],
          ["e", :add],
          ["f", :add],
          ["c", :delete],
          ["g", :add],
          ["d", :delete],
        ],
      )
    end
  end
end