dojopi

Gemfile

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+# A sample Gemfile
+source "https://rubygems.org"
+
+ gem "rspec"

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    diff-lcs (1.1.3)
+    rspec (2.10.0)
+      rspec-core (~> 2.10.0)
+      rspec-expectations (~> 2.10.0)
+      rspec-mocks (~> 2.10.0)
+    rspec-core (2.10.1)
+    rspec-expectations (2.10.0)
+      diff-lcs (~> 1.1.3)
+    rspec-mocks (2.10.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  rspec

lib/clipboard.rb

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+class Clipboard
+  attr_accessor :commands, :last_commands
+
+  def initialize
+    @commands = []
+    @last_commands = []
+  end
+
+  def undo
+    @last_commands << @commands.pop
+    self
+  end
+
+  def redo
+    @commands << @last_commands.pop
+    self
+  end
+end

spec/clipboard_spec.rb

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+require 'spec_helper'
+
+describe Clipboard do
+  let :mkdir do
+    double(:name => 'mkdir')
+  end
+
+  let :ls do
+    double(:name => 'ls')
+  end
+
+  before do
+    subject.commands << mkdir
+  end
+
+  it 'should respond to undo' do
+    subject.should respond_to :undo
+  end
+
+  it 'should add last_undo command' do
+    subject.undo
+    subject.commands.should be_empty
+  end
+
+  it 'should readdd last undo command on redo' do
+    subject.undo.redo
+    subject.commands.should == [mkdir]
+  end
+
+  it 'should return self when call undo' do
+    subject.undo.should eq subject
+  end
+
+  it 'should return self when call redo' do
+    subject.redo.should eq subject
+  end
+
+  it 'should undo twice and redo' do
+    subject.commands << ls
+    subject.undo.undo.redo.redo
+    subject.commands.should == [mkdir,ls]
+    subject.last_commands.should be_empty
+  end
+end

spec/spec_helper.rb

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+require 'lib/clipboard'