Add equality mutations

* Closes #132

Changelog.md

@@ -3,6 +3,8 @@
 Changes:
 
 * Remove dependency to descendants tracker
+* Add mutation #== => #eql?, #equal?
+* Add mutation #eql? =>  #equal?
 
 # v0.5.9 2014-03-28
 

lib/mutant.rb

@@ -21,8 +21,10 @@ require 'morpher'
 
 # Library namespace
 module Mutant
-  # The empty string used within this namespace
+  # The frozen empty string used within mutant
   EMPTY_STRING = ''.freeze
+  # The frozen empty array used within mutant
+  EMPTY_ARRAY = [].freeze
 end # Mutant
 
 require 'mutant/version'

lib/mutant/mutator/node/send.rb

@@ -11,10 +11,12 @@ module Mutant
 
         children :receiver, :selector
 
-        SELECTOR_REPLACEMENTS = {
-          send: :public_send,
-          gsub: :sub
-        }.freeze
+        SELECTOR_REPLACEMENTS = IceNine.deep_freeze(
+          send:  [:public_send],
+          gsub:  [:sub],
+          eql?:  [:equal?],
+          :== => [:eql?, :equal?]
+        )
 
         INDEX_REFERENCE = :[]
         INDEX_ASSIGN    = :[]=
@@ -118,8 +120,9 @@ module Mutant
         # @api private
         #
         def emit_selector_replacement
-          replacement = SELECTOR_REPLACEMENTS.fetch(selector) { return }
-          emit_selector(replacement)
+          SELECTOR_REPLACEMENTS.fetch(selector, EMPTY_ARRAY).each do |replacement|
+            emit_selector(replacement)
+          end
         end
 
         # Emit naked receiver mutation

lib/mutant/mutator/node/send/binary.rb

@@ -21,6 +21,7 @@ module Mutant
           def dispatch
             emit(left)
             emit_left_mutations
+            emit_selector_replacement
             emit(right) unless right.type == :splat
             emit_right_mutations
           end

spec/unit/mutant/mutator/node/send_spec.rb

@@ -5,6 +5,24 @@ require 'spec_helper'
 # FIXME: This spec needs to be structured better!
 describe Mutant::Mutator, 'send' do
 
+  context 'when using #==' do
+    let(:source) { 'foo == bar' }
+
+    let(:mutations) do
+      mutations = []
+      mutations << 'foo'
+      mutations << 'bar'
+      mutations << 'nil == bar'
+      mutations << 'foo == nil'
+      mutations << 'nil'
+      mutations << 'foo.eql?(bar)'
+      mutations << 'foo.equal?(bar)'
+    end
+
+    it_should_behave_like 'a mutator'
+  end
+
+
   context 'when using #gsub' do
     let(:source) { 'foo.gsub(a, b)' }
 
@@ -297,7 +315,7 @@ describe Mutant::Mutator, 'send' do
         it_should_behave_like 'a mutator'
       end
 
-      Mutant::BINARY_METHOD_OPERATORS.each do |operator|
+      (Mutant::BINARY_METHOD_OPERATORS - [:==, :eql?]).each do |operator|
         context 'on literal scalar arguments' do
           let(:source) { "true #{operator} false" }