String Tokenizer Kata for Code Retreat

string_tokenizer.rb

module StringTokenizer
  VERSION = '0.0.1'
  def tokenize(context)
    self.gsub(/\$[^ ]*/) {|match|
        context[match[1..-1].to_sym]
      }
  end
end

string_tokenizer_specs.rb

describe StringTokenizer do
  def tokenize(string, context = {})
    string.extend(StringTokenizer).tokenize(context)
  end
  context "with no tokens" do
   it "returns blank string if given string is blank" do
     tokenize("").should == ""
   end
   it "returns non-blank string unchanged" do
     tokenize("hello, world").should == "hello, world"
   end
  end
  context "with one token" do
    it "replaces token with empty string if no value in context" do
      tokenize("$name is cool").should == " is cool"
    end
    it "replaces token with value from context" do
      tokenize("$name", :name => 'corey').should == 'corey'
    end
    it "leaves rest of string unchanged" do
      tokenize("$name is cool", :name => 'corey').should == 'corey is cool'
    end
  end
  context "with two tokens" do
    it "replaces each token with the value from the context" do
      tokenize("$name loves $food", :name => 'corey', :food => 'bacon').should ==
              "corey loves bacon"
    end
    it "replaces with blank string the tokens that have no value in context" do
      tokenize("$name loves $food1 and $food2", :name => 'corey').should ==
      "corey loves  and "

    end
  end
end