Remove guard via identity

* Simplify spec helper via mutation verifier class
* There was no need to guard via mapped identity anymore.

Gemfile

@@ -4,6 +4,8 @@ source 'https://rubygems.org'
 
 gem 'mutant', path: '.'
 
+gem 'unparser', git: 'https://github.com/mbj/unparser.git'
+
 gemspec name: 'mutant'
 
 gem 'devtools', git: 'https://github.com/rom-rb/devtools.git'

lib/mutant/mutator.rb

@@ -33,18 +33,6 @@ module Mutant
     end
     private_class_method :handle
 
-    # Return identity of object (for deduplication)
-    #
-    # @param [Object] object
-    #
-    # @return [Object]
-    #
-    # @api private
-    #
-    def self.identity(object)
-      object
-    end
-
     # Return input
     #
     # @return [Object]
@@ -92,7 +80,7 @@ module Mutant
     # @api private
     #
     def new?(object)
-      !@seen.include?(identity(object))
+      !@seen.include?(object)
     end
 
     # Add object to guarded values
@@ -104,19 +92,7 @@ module Mutant
     # @api private
     #
     def guard(object)
-      @seen << identity(object)
-    end
-
-    # Return identity for input
-    #
-    # @param [Object] input
-    #
-    # @return [Object]
-    #
-    # @api private
-    #
-    def identity(input)
-      self.class.identity(input)
+      @seen << object
     end
 
     # Dispatch node generations

lib/mutant/mutator/node/rescue.rb

@@ -8,18 +8,6 @@ module Mutant
 
         handle :rescue
 
-        # Return identity
-        #
-        # @param [Parser::AST::Node] node
-        #
-        # @return [String]
-        #
-        # @api private
-        #
-        def self.identity(node)
-          super(NodeHelpers.s(:kwbegin, node))
-        end
-
       end # Rescue
     end # Node
   end # Mutator

lib/mutant/node_helpers.rb

@@ -18,13 +18,13 @@ module Mutant
     module_function :s
 
     NAN =
-      s(:send, s(:float,  0.0), :/, s(:args, s(:float, 0.0)))
+      s(:send, s(:float,  0.0), :/, s(:float, 0.0))
     INFINITY =
-      s(:send, s(:float,  1.0), :/, s(:args, s(:float, 0.0)))
+      s(:send, s(:float,  1.0), :/, s(:float, 0.0))
     NEW_OBJECT =
       s(:send, s(:const, s(:cbase), :Object), :new)
     NEGATIVE_INFINITY =
-      s(:send, s(:float, -1.0), :/, s(:args, s(:float, 0.0)))
+      s(:send, s(:float, -1.0), :/, s(:float, 0.0))
 
     RAISE             = s(:send, nil, :raise)
 

spec/shared/mutator_behavior.rb

@@ -1,52 +1,12 @@
-# encoding: utf-8
-
-class Subject
-
-  include Equalizer.new(:source)
-
-  Undefined = Object.new.freeze
-
-  attr_reader :source
-
-  def self.coerce(input)
-    case input
-    when Parser::AST::Node
-      new(input)
-    when String
-      new(Parser::CurrentRuby.parse(input))
-    else
-      raise
-    end
-  end
-
-  def to_s
-    "#{@node.inspect}\n#{@source}"
-  end
-
-  def initialize(node)
-    source = Unparser.unparse(node)
-    @node, @source = node, source
-  end
-
-  def assert_transitive!
-    generated = Unparser.generate(@node)
-    parsed    = Parser::CurrentRuby.parse(generated)
-    again     = Unparser.generate(parsed)
-    unless generated == again
-      # mostly an unparser bug!
-      fail sprintf("Untransitive:\n%s\n---\n%s", generated, again)
-    end
-    self
-  end
-end
+# encoding: UTF-8
 
 shared_examples_for 'a mutator' do
-  subject { object.each(node) { |item| yields << item } }
+  subject { object.each(node, &yields.method(:<<)) }
 
   let(:yields) { []              }
   let(:object) { described_class }
 
-  unless instance_methods.map(&:to_s).include?('node')
+  unless instance_methods.include?(:node)
     let(:node) { parse(source) }
   end
 
@@ -57,42 +17,32 @@ shared_examples_for 'a mutator' do
 
     it { should be_instance_of(to_enum.class) }
 
-    let(:expected_mutations) do
-      mutations.map(&Subject.method(:coerce))
+    def coerce(input)
+      case input
+      when String
+        Parser::CurrentRuby.parse(input)
+      when Parser::AST::Node
+        input
+      else
+        raise
+      end
     end
 
-    let(:generated_mutations) do
+    def normalize(node)
+      Unparser::Preprocessor.run(node)
+    end
+
+    let(:expected_mutations) do
+      mutations.map(&method(:coerce)).map(&method(:normalize))
     end
 
     it 'generates the expected mutations' do
+      generated_mutations = subject.map(&method(:normalize))
 
-      generated  = subject.map { |node| Subject.new(node) }
+      verifier = MutationVerifier.new(node, expected_mutations, generated_mutations)
 
-      missing    = expected_mutations - generated
-      unexpected = generated - expected_mutations
-
-      message = []
-
-      if missing.any?
-        message << sprintf('Missing mutations (%i):', missing.length)
-        message.concat(missing)
-      end
-
-      if unexpected.any?
-        message << sprintf('Unexpected mutations (%i):', unexpected.length)
-        message.concat(unexpected)
-      end
-
-      if message.any?
-
-        message = sprintf(
-          "Original:\n%s\n%s\n-----\n%s",
-          generate(node),
-          node.inspect,
-          message.join("\n-----\n")
-        )
-
-        fail message
+      unless verifier.success?
+        fail verifier.error_report
       end
     end
   end

spec/spec_helper.rb

@@ -21,8 +21,10 @@ if ENV['COVERAGE'] == 'true'
   end
 end
 
-require 'equalizer'
+require 'concord'
+require 'adamantium'
 require 'devtools/spec_helper'
+require 'unparser/cli'
 require 'mutant'
 
 $LOAD_PATH << File.join(TestApp.root, 'lib')

spec/support/mutation_verifier.rb

@@ -0,0 +1,96 @@
+# encoding: UTF-8
+
+class MutationVerifier
+  include Adamantium::Flat, Concord.new(:original_node, :expected, :generated)
+
+  # Test if mutation was verified successfully
+  #
+  # @return [Boolean]
+  #
+  # @api private
+  #
+  def success?
+    unparser.success? && missing.empty? && unexpected.empty?
+  end
+
+  # Return error report
+  #
+  # @return [String]
+  #
+  # @api private
+  #
+  def error_report
+    unless unparser.success?
+      return unparser.error_report
+    end
+    mutation_report
+  end
+
+private
+
+  # Return unexpected mutationso
+  #
+  # @return [Array<Parser::AST::Node>]
+  #
+  # @api private
+  #
+  def unexpected
+    generated - expected
+  end
+  memoize :unexpected
+
+  # Return mutation report
+  #
+  # @return [String]
+  #
+  # @api private
+  #
+  def mutation_report
+    message = ['Original:', original_node.inspect]
+    if missing.any?
+      message << 'Missing mutations:'
+      message << missing.map(&method(:format_mutation)).join("\n-----\n")
+    end
+    if unexpected.any?
+      message << 'Unexpected mutations:'
+      message << unexpected.map(&method(:format_mutation)).join("\n-----\n")
+    end
+    message.join("\n======\n")
+  end
+
+  # Format mutation
+  #
+  # @return [String]
+  #
+  # @api private
+  #
+  def format_mutation(node)
+    [
+      node.inspect,
+      Unparser.unparse(node)
+    ].join("\n")
+  end
+
+  # Return missing mutationso
+  #
+  # @return [Array<Parser::AST::Node>]
+  #
+  # @api private
+  #
+  def missing
+    expected - generated
+  end
+  memoize :missing
+
+  # Return unparser verifier
+  #
+  # @return [Unparser::CLI::Source]
+  #
+  # @api private
+  #
+  def unparser
+    Unparser::CLI::Source::Node.new(original_node)
+  end
+  memoize :unparser
+end # MutationVerifier
+