require "benchmark"
require "helper"

describe Twitter::Utils do
  describe "#pmap" do
    it "returns an array" do
      expect(subject.flat_pmap([], &:reverse)).to be_an(Array)
    end

    it "behaves like map" do
      array = (0..9).to_a
      block = proc { |x| x + 1 }
      expect(subject.pmap(array, &block)).to eq(array.collect(&block))
    end

    it "maps in parallel" do
      delay = 0.1
      array = (0..9).to_a
      size  = array.size
      block = proc { |x| sleep(delay) && (x + 1) }
      block_without_sleep = proc { |x| x + 1 }
      expected = array.collect(&block_without_sleep)
      elapsed_time = Benchmark.realtime do
        expect(subject.pmap(array, &block)).to eq(expected)
      end
      expect(elapsed_time).to be_between(delay, delay * size)
    end
  end

  describe "#flat_pmap" do
    it "always returns an array" do
      expect(subject.flat_pmap([], &:reverse)).to be_an(Array)
    end

    it "behaves like map for a flat array" do
      array = (0..9).to_a
      block = proc { |x| x + 1 }
      expect(subject.flat_pmap(array, &block)).to eq(array.collect(&block))
    end

    it "behaves like flat_map" do
      array = (0..4).to_a.combination(2).to_a
      block = proc { |x| x.reverse }
      expect(subject.flat_pmap(array, &block)).to eq(array.flat_map(&block))
    end

    it "flat maps in parallel" do
      delay = 0.1
      array = (0..4).to_a.combination(2).to_a
      size  = array.size
      block = proc { |x| sleep(delay) && x.reverse }
      block_without_sleep = proc(&:reverse)
      expected = array.flat_map(&block_without_sleep)
      elapsed_time = Benchmark.realtime do
        expect(subject.flat_pmap(array, &block)).to eq(expected)
      end
      expect(elapsed_time).to be_between(delay, delay * size)
    end
  end
end
