Add colorized diffs to cli reporter

lib/mutant.rb

@@ -4,6 +4,9 @@ require 'securerandom'
 require 'to_source'
 require 'ice_nine'
 require 'backports'
+require 'diff/lcs'
+require 'diff/lcs/hunk'
+require 'pp'
 
 # Library namespace
 module Mutant
@@ -72,6 +75,8 @@ require 'mutant/matcher/method/classifier'
 require 'mutant/killer'
 require 'mutant/killer/rspec'
 require 'mutant/runner'
+require 'mutant/color'
+require 'mutant/differ'
 require 'mutant/reporter'
 require 'mutant/reporter/null'
 require 'mutant/reporter/cli'

lib/mutant/color.rb

@@ -0,0 +1,27 @@
+module Mutant
+  # Class to colorize strings
+  class Color
+    include Immutable
+
+    def initialize(code)
+      @code = code
+    end
+
+    def format(text)
+      "\e[#{@code}m#{text}\e[0m"
+    end
+
+    NONE = Class.new(self) do
+      def initialize(*)
+      end
+
+      def format(text)
+        text
+      end
+    end.new.freeze
+
+    RED   = Color.new(31)
+    GREEN = Color.new(32)
+    BLUE  = Color.new(34)
+  end
+end

lib/mutant/differ.rb

@@ -0,0 +1,54 @@
+module Mutant
+  class Differ
+    include Immutable
+
+    def initialize(old, new)
+      @new, @old = new.lines.map(&:chomp), old.lines.map(&:chomp)
+      @diffs = Diff::LCS.diff(@old, @new)
+    end
+
+    def format
+      :unified
+    end
+
+    def context_lines
+      3
+    end
+
+    def length_difference
+      @new.size - @old.size
+    end
+
+    def diff
+      output = ''
+      @diffs.each do |piece|
+        hunk = Diff::LCS::Hunk.new(@old, @new, piece, context_lines, length_difference)
+        output << hunk.diff(format)
+        output << "\n"
+      end
+      output
+    end
+    memoize :diff
+
+    def colorized_diff
+      diff.lines.map do |line|
+        self.class.colorize_line(line)
+      end.join
+    end
+    memoize :colorized_diff
+
+    def self.colorize_line(line)
+      case line[0].chr
+      when '+'
+        Color::GREEN
+      when '-'
+        Color::RED
+      when '@'
+        line[1].chr == '@' ? Color::BLUE : Color::NONE
+      else
+        Color::NONE
+      end.format(line)
+    end
+  end
+end
+

lib/mutant/reporter/cli.rb

@@ -11,7 +11,7 @@ module Mutant
       # @api private
       #
       def subject(subject)
-        @io.puts("Found subject: #{subject.identification}")
+        @io.puts("Subject: #{subject.identification}")
       end
 
       # Report mutations 
@@ -35,14 +35,15 @@ module Mutant
       # @api private
       #
       def killer(killer)
-        @io.puts('Killer: %s / %02.2fs' % [killer.identification,killer.runtime])
-
         if killer.fail?
-          @io.puts "Uncovered mutation"
+          @io.puts(colorize(Color::RED, "!!! Uncovered Mutation !!!"))
-          @io.puts "=== Original ===\n#{killer.original_source}"
+          differ = Differ.new(killer.original_source,killer.mutation_source)
+          diff = color? ? differ.colorized_diff : color
+          @io.puts(diff)
           @io.puts
-          @io.puts "=== Mutation ===\n#{killer.mutation_source}"
         end
+
+        self
       end
 
     private 
@@ -58,6 +59,47 @@ module Mutant
       def initialize(io)
         @io = io
       end
+
+      # Test for colored output
+      #
+      # @return [true]
+      #   returns true if output is colored
+      #
+      # @return [false]
+      #   returns false otherwise
+      #
+      # @api private
+      #
+      def color?
+        tty?
+      end
+
+      # Colorize message
+      #
+      # @param [Color] color
+      # @param [String] message
+      #
+      # @api private
+      #
+      def colorize(color, message)
+        color = Color::NONE unless color?
+        color.format(message)
+      end
+
+      # Test for output to tty
+      #
+      # @return [true]
+      #   returns true if output is a tty
+      # 
+      # @return [false]
+      #   returns false otherwise
+      #
+      # @api private
+      #
+      def tty?
+        @io.respond_to?(:tty?) && @io.tty?
+      end
+      memoize :tty?
     end
   end
 end

mutant.gemspec

@@ -21,4 +21,5 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency('backports', '~> 2.6')
   gem.add_runtime_dependency('immutable', '~> 0.0.1')
   gem.add_runtime_dependency('abstract',  '~> 0.0.1')
+  gem.add_runtime_dependency('diff-lcs',  '~> 1.1.3')
 end

spec/integration/mutant/differ_spec.rb

@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+describe Mutant,'differ' do
+  specify 'allows to create diffs from text' do
+    a = "Foo\nBar\n"
+    b = "Foo\nBaz\n"
+    differ = Mutant::Differ.new(a,b)
+    differ.diff.should == strip_indent(<<-RUBY)
+      @@ -1,3 +1,3 @@
+       Foo
+      -Bar
+      +Baz
+    RUBY
+  end
+end

spec/spec_helper.rb

@@ -11,4 +11,5 @@ require 'test_app'
 require 'mutant'
 
 RSpec.configure do |config|
+  config.include(CompressHelper)
 end

spec/support/compress_helper.rb

@@ -0,0 +1,10 @@
+module CompressHelper
+  def strip_indent(string)
+    lines = string.lines
+    match = /\A( *)/.match(lines.first)
+    whitespaces = match[1].to_s.length
+    stripped = lines.map do |line|
+      line[whitespaces..-1]
+    end.join
+  end
+end