Merge pull request #694 from adimasuhid/features/implement-rotational-cipher

rotational-cipher: Implement Rotational Cipher

Author: Insti

config.json

@@ -859,6 +859,19 @@
         "Mathematics"
       ]
     },
+    {
+      "uuid": "af5ccf14-eff2-4dc6-b1db-e209cddca62a",
+      "slug": "rotational-cipher",
+      "core": false,
+      "unlocked_by": null,
+      "difficulty": 1,
+      "topics": [
+        "Control-flow (conditionals)",
+        "Control-flow (loops)",
+        "Logic",
+        "Strings"
+      ]
+    },
     {
       "uuid": "cae4e000-3aac-41f7-b727-f9cce12d058d",
       "slug": "octal",

exercises/rotational-cipher/.meta/.version

@@ -0,0 +1 @@
+1

exercises/rotational-cipher/.meta/generator/rotational_cipher_case.rb

@@ -0,0 +1,9 @@
+require 'generator/exercise_case'
+
+class RotationalCipherCase < Generator::ExerciseCase
+
+  def workload
+    assert_equal { %Q[RotationalCipher.rotate("#{text}", #{shiftKey})] }
+  end
+
+end

exercises/rotational-cipher/.meta/solutions/rotational_cipher.rb

@@ -0,0 +1,53 @@
+module BookKeeping
+  VERSION = 1
+end
+
+class RotationalCipher
+  SMALL_LETTERS_RANGE = (97..122)
+  BIG_LETTERS_RANGE   = (65..90)
+  ROTATION_MODIFIER   = 1
+
+  attr_reader :text
+
+  def initialize(text, key)
+    @text      = text
+    @shift_key = key
+  end
+
+  def self.rotate(text, key)
+    new(text, key).rotate
+  end
+
+  def rotate
+    text.split('').map { |char| shift_char(char) }.join
+  end
+
+  private
+
+  def shift_char(char)
+    shift_ascii(char.ord).chr
+  end
+
+  def shift_key
+    @shift_key % 26
+  end
+
+  def shift_ascii(char_ascii)
+    case char_ascii
+    when SMALL_LETTERS_RANGE
+      shift_within(char_ascii, SMALL_LETTERS_RANGE.min, SMALL_LETTERS_RANGE.max)
+    when BIG_LETTERS_RANGE
+      shift_within(char_ascii, BIG_LETTERS_RANGE.min, BIG_LETTERS_RANGE.max)
+    else
+      char_ascii
+    end
+  end
+
+  def shift_within(char_ascii, lower_limit, upper_limit)
+    shifted_ascii = char_ascii + shift_key
+
+    return shifted_ascii if shifted_ascii <= upper_limit
+
+    lower_limit + (shifted_ascii - upper_limit - ROTATION_MODIFIER)
+  end
+end

exercises/rotational-cipher/rotational_cipher_test.rb

@@ -0,0 +1,77 @@
+require 'minitest/autorun'
+require_relative 'rotational_cipher'
+
+# Common test data version: 1.1.0 9c658d1
+class RotationalCipherTest < Minitest::Test
+  def test_rotate_a_by_0_same_output_as_input
+    # skip
+    assert_equal "a", RotationalCipher.rotate("a", 0)
+  end
+
+  def test_rotate_a_by_1
+    skip
+    assert_equal "b", RotationalCipher.rotate("a", 1)
+  end
+
+  def test_rotate_a_by_26_same_output_as_input
+    skip
+    assert_equal "a", RotationalCipher.rotate("a", 26)
+  end
+
+  def test_rotate_m_by_13
+    skip
+    assert_equal "z", RotationalCipher.rotate("m", 13)
+  end
+
+  def test_rotate_n_by_13_with_wrap_around_alphabet
+    skip
+    assert_equal "a", RotationalCipher.rotate("n", 13)
+  end
+
+  def test_rotate_capital_letters
+    skip
+    assert_equal "TRL", RotationalCipher.rotate("OMG", 5)
+  end
+
+  def test_rotate_spaces
+    skip
+    assert_equal "T R L", RotationalCipher.rotate("O M G", 5)
+  end
+
+  def test_rotate_numbers
+    skip
+    assert_equal "Xiwxmrk 1 2 3 xiwxmrk", RotationalCipher.rotate("Testing 1 2 3 testing", 4)
+  end
+
+  def test_rotate_punctuation
+    skip
+    assert_equal "Gzo'n zvo, Bmviyhv!", RotationalCipher.rotate("Let's eat, Grandma!", 21)
+  end
+
+  def test_rotate_all_letters
+    skip
+    assert_equal "Gur dhvpx oebja sbk whzcf bire gur ynml qbt.", RotationalCipher.rotate("The quick brown fox jumps over the lazy dog.", 13)
+  end
+
+  # Problems in exercism evolve over time, as we find better ways to ask
+  # questions.
+  # The version number refers to the version of the problem you solved,
+  # not your solution.
+  #
+  # Define a constant named VERSION inside of the top level BookKeeping
+  # module, which may be placed near the end of your file.
+  #
+  # In your file, it will look like this:
+  #
+  # module BookKeeping
+  #   VERSION = 1 # Where the version number matches the one in the test.
+  # end
+  #
+  # If you are curious, read more about constants on RubyDoc:
+  # http://ruby-doc.org/docs/ruby-doc-bundle/UsersGuide/rg/constants.html
+
+  def test_bookkeeping
+    skip
+    assert_equal 1, BookKeeping::VERSION
+  end
+end