String#reverse_words & #longest_run

string-additions.rb

require 'rspec'

class String
  if method_defined? :reverse_words
    raise "String#reverse_words is already defined"
  end
  def reverse_words
    split(' ').reverse!.join(' ')
  end

  if method_defined? :longest_run
    raise "String#longest_run is already defined"
  end
  def longest_run
    return 0 if empty?
    max_count = 1
    tmp_count = 1
    tmp_char = nil # previous character
    each_char do |c|
      if tmp_char == c
        tmp_count += 1
        max_count = [max_count, tmp_count].max
      else
        tmp_count = 1
      end
      tmp_char = c
    end
    max_count
  end
end

describe String do
  describe "#reverse_words" do
    # specify { "hello".reverse_words.should eq("hello") }
    # specify { "hello world".reverse_words.should eq("world hello") }
    # specify { "bob & pop run".reverse_words.should eq("run pop & bob") }

    strings = {
      "hello"         => "hello",
      "hello world"   => "world hello",
      "bob & pop run" => "run pop & bob"
    }

    strings.each do |k, v|
      specify "\"#{k}\" => \"#{v}\"" do
        k.reverse_words.should eq(v)
      end
    end
  end

  describe "#longest_run" do
    # specify { "".longest_run.should equal(0) }
    # specify { "a".longest_run.should equal(1) }
    # specify { "ab".longest_run.should equal(1) }
    # specify { "aab".longest_run.should equal(2) }
    # specify { "abbbaabb".longest_run.should equal(3) }

    strings = {
      ""         => 0,
      "a"        => 1,
      "ab"       => 1,
      "abb"      => 2,
      "abbbaabb" => 3
    }

    strings.each do |k, v|
      specify "\"#{k}\" => \"#{v}\"" do
        k.longest_run.should equal(v)
      end
    end
  end
end