fffff.rb

# coding: utf-8
# https://gist.github.com/JunichiIto/c548e39fed60bf4bd36a
require 'byebug'
require 'rspec'
class KaraokeMachine
  KEYBOARD = %w(C C# D D# E F F# G G# A A# B)
  def initialize(melody)
    @melody = melody
  end

  def transpose(amount)
    @melody.scan(/.(?:#)?/).map do |ch|
      if KEYBOARD.include?(ch)
        index = KEYBOARD.index(ch)
        (KEYBOARD * 2)[index + amount % 12]
      else
        ch
      end
    end.join
  end
end

describe KaraokeMachine do
  it "メロディ無し" do
    melody = ""
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(0)).to eq answer
  end

  # ここから下のコメントを外していって、テストを全部パスさせてください！

  it "変更無し" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(0)).to eq answer
  end
  #
  it "2上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "D E F# G |F# E D   |F# G A B |A G F#   |D   D   |D   D   |DDEEF#F#GG|F# E D   "
    expect(KaraokeMachine.new(melody).transpose(2)).to eq answer
  end
  #
  it "7上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "G A B C |B A G   |B C D E |D C B   |G   G   |G   G   |GGAABBCC|B A G   "
    expect(KaraokeMachine.new(melody).transpose(7)).to eq answer
  end
  #
  it "1下げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "B C# D# E |D# C# B   |D# E F# G# |F# E D#   |B   B   |B   B   |BBC#C#D#D#EE|D# C# B   "
    expect(KaraokeMachine.new(melody).transpose(-1)).to eq answer
  end

  it "7下げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "F G A A# |A G F   |A A# C D |C A# A   |F   F   |F   F   |FFGGAAA#A#|A G F   "
    expect(KaraokeMachine.new(melody).transpose(-7)).to eq answer
  end

  it "1オクターブ上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(12)).to eq answer
  end

  it "1オクターブ下げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(-12)).to eq answer
  end

  it "14上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "D E F# G |F# E D   |F# G A B |A G F#   |D   D   |D   D   |DDEEF#F#GG|F# E D   "
    expect(KaraokeMachine.new(melody).transpose(14)).to eq answer
  end

  it "13下げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "B C# D# E |D# C# B   |D# E F# G# |F# E D#   |B   B   |B   B   |BBC#C#D#D#EE|D# C# B   "
    expect(KaraokeMachine.new(melody).transpose(-13)).to eq answer
  end

  it "2オクターブ上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(24)).to eq answer
  end

  it "2オクターブ下げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = melody
    expect(KaraokeMachine.new(melody).transpose(-24)).to eq answer
  end

  it "26上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "D E F# G |F# E D   |F# G A B |A G F#   |D   D   |D   D   |DDEEF#F#GG|F# E D   "
    expect(KaraokeMachine.new(melody).transpose(26)).to eq answer
  end

  it "25上げる" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    answer = "B C# D# E |D# C# B   |D# E F# G# |F# E D#   |B   B   |B   B   |BBC#C#D#D#EE|D# C# B   "
    expect(KaraokeMachine.new(melody).transpose(-25)).to eq answer
  end

  it "6上げる(メロディはF#から開始)" do
    melody = "F# G# A# B |A# G# F#   |A# B C# D# |C# B A#   |F#   F#   |F#   F#   |F#F#G#G#A#A#BB|A# G# F#   "
    answer = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    expect(KaraokeMachine.new(melody).transpose(6)).to eq answer
  end

  it "6下げる(メロディはF#から開始)" do
    melody = "F# G# A# B |A# G# F#   |A# B C# D# |C# B A#   |F#   F#   |F#   F#   |F#F#G#G#A#A#BB|A# G# F#   "
    answer = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    expect(KaraokeMachine.new(melody).transpose(-6)).to eq answer
  end

  it "連続してtransposeを呼び出す" do
    melody = "C D E F |E D C   |E F G A |G F E   |C   C   |C   C   |CCDDEEFF|E D C   "
    karaoke = KaraokeMachine.new(melody)

    answer = melody
    expect(karaoke.transpose(0)).to eq answer

    answer = "D E F# G |F# E D   |F# G A B |A G F#   |D   D   |D   D   |DDEEF#F#GG|F# E D   "
    expect(karaoke.transpose(2)).to eq answer

    answer = "B C# D# E |D# C# B   |D# E F# G# |F# E D#   |B   B   |B   B   |BBC#C#D#D#EE|D# C# B   "
    expect(karaoke.transpose(-1)).to eq answer
  end
end

Gemfile

# A sample Gemfile
source 'https://rubygems.org'

gem 'rspec'
gem 'byebug'

Gemfile.lock

GEM
  remote: https://rubygems.org/
  specs:
    byebug (3.1.2)
      columnize (~> 0.8)
      debugger-linecache (~> 1.2)
    columnize (0.8.9)
    debugger-linecache (1.2.0)
    diff-lcs (1.2.5)
    rspec (3.0.0)
      rspec-core (~> 3.0.0)
      rspec-expectations (~> 3.0.0)
      rspec-mocks (~> 3.0.0)
    rspec-core (3.0.2)
      rspec-support (~> 3.0.0)
    rspec-expectations (3.0.2)
      diff-lcs (>= 1.2.0, < 2.0)
      rspec-support (~> 3.0.0)
    rspec-mocks (3.0.2)
      rspec-support (~> 3.0.0)
    rspec-support (3.0.2)

PLATFORMS
  ruby

DEPENDENCIES
  byebug
  rspec