Implement the core of question one (simple shift cypher), and set up …

…autotest/rspec.

.rspec

@@ -0,0 +1,3 @@
+.rspec
+--format nested
+--color

Rakefile

@@ -8,4 +8,4 @@ namespace :quiz do
     puts "Question #1: #{first_question}."
     system("open #{first_question.reference_url}")
   end
-end
+end

autotest/discover.rb

@@ -0,0 +1 @@
+Autotest.add_discovery { "rspec2" }

minisculus/question-1/question_one.rb

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+module Minisculus
+  module QuestionOne
+    class MarkI
+      def initialize(key, character_set = default_character_set)
+        @key, @character_set = key, character_set
+      end
+
+      def decrypt(chars)
+        chars.each_char.map { |char| transpose(char) }.join
+      end
+
+      private
+
+      def transpose(char)
+        index = @character_set.index(char) + @key
+        @character_set[index - @character_set.length]
+      end
+
+      def default_character_set
+        [
+          "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
+          "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
+          "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z",
+          "a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m",
+          "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z",
+          ".", ",", "?", "!", "'", "\"", " "
+        ]
+      end
+    end
+  end
+end
+
+if __FILE__ == $0
+end

spec/question_one_spec.rb

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+require 'spec_helper'
+require 'question-1/question_one'
+
+describe "Mark I machine" do # basic ceasar/shift cypher
+  include Minisculus::QuestionOne
+
+  it "should shift a character in a set by the given key when decrypting" do
+    Minisculus::QuestionOne::MarkI.new(1, %w{a b c}).decrypt("a").should == "b"
+    Minisculus::QuestionOne::MarkI.new(2, %w{a b c}).decrypt("a").should == "c"
+  end
+
+  it "should shift multiple characters in a set by the given key" do
+    Minisculus::QuestionOne::MarkI.new(1, %w{a b c}).decrypt("ab").should == "bc"
+  end
+
+  it "should go back to the beginning of the set when shifting moves off the end of the set" do
+    Minisculus::QuestionOne::MarkI.new(2, %w{a b c}).decrypt("b").should == "a"
+    Minisculus::QuestionOne::MarkI.new(1, %w{a b c}).decrypt("bc").should == "ca"
+  end
+
+end

spec/spec_helper.rb

@@ -0,0 +1,2 @@
+require 'rspec'
+$LOAD_PATH.unshift(File.join(File.dirname(__FILE__), *%w[.. minisculus]))