Fix coverage of Mutant::Mutator namespace

Rakefile

@@ -9,14 +9,13 @@ namespace :metrics do
   task mutant: :coverage do
     arguments = %w[
       bundle exec mutant
-      --ignore-subject Mutant::Meta*
       --include lib
       --since HEAD~1
       --require mutant
       --use rspec
       --zombie
     ]
-    arguments.concat(%w[--jobs 4]) if ENV.key?('CIRCLE_CI')
+    arguments.concat(%w[--jobs 4]) if ENV.key?('CIRCLECI')
 
     arguments.concat(%w[-- Mutant*])
 

config/flay.yml

@@ -1,3 +1,3 @@
 ---
-threshold: 18
-total_score: 1162
+threshold: 16
+total_score: 1160

lib/mutant.rb

@@ -91,7 +91,6 @@ def self.ci?
 require 'mutant/mutator/node/literal/nil'
 require 'mutant/mutator/node/argument'
 require 'mutant/mutator/node/arguments'
-require 'mutant/mutator/node/blockarg'
 require 'mutant/mutator/node/begin'
 require 'mutant/mutator/node/binary'
 require 'mutant/mutator/node/const'
@@ -112,7 +111,6 @@ def self.ci?
 require 'mutant/mutator/node/yield'
 require 'mutant/mutator/node/super'
 require 'mutant/mutator/node/zsuper'
-require 'mutant/mutator/node/restarg'
 require 'mutant/mutator/node/send'
 require 'mutant/mutator/node/send/binary'
 require 'mutant/mutator/node/send/conditional'

lib/mutant/ast/meta/send.rb

@@ -18,6 +18,7 @@ class Send
         #
         # @return [Enumerable<Parser::AST::Node>]
         alias_method :arguments, :remaining_children
+
         public :arguments
 
         # Test if AST node is a valid assignment target

lib/mutant/meta/example.rb

@@ -22,7 +22,7 @@ def source
       #
       # @return [Enumerable<Mutant::Mutation>]
       def generated
-        Mutator.each(node).map do |node|
+        Mutator::REGISTRY.call(node).map do |node|
           Mutation::Evil.new(self, node)
         end
       end

lib/mutant/mutator.rb

@@ -1,42 +1,22 @@
 module Mutant
   # Generator for mutations
   class Mutator
-    include Adamantium::Flat, AbstractType
-
-    # Run mutator on input
-    #
-    # @param [Object] input
-    #   the input to mutate
-    #
-    # @param [Mutator] parent
-    #
-    # @return [self]
-    def self.each(input, parent = nil, &block)
-      return to_enum(__method__, input, parent) unless block_given?
-      REGISTRY.lookup(input).new(input, parent, block)
-
-      self
-    end
+    include Adamantium::Flat, Concord.new(:input, :parent), AbstractType, Procto.call(:output)
 
     # Register node class handler
     #
     # @return [undefined]
     def self.handle(*types)
       types.each do |type|
-        REGISTRY.register(type, self)
+        self::REGISTRY.register(type, self)
       end
     end
     private_class_method :handle
 
-    # Mutation input
-    #
-    # @return [Object]
-    attr_reader :input
-
-    # Parent context of input
+    # Return output
     #
-    # @return [Object]
-    attr_reader :parent
+    # @return [Set<Parser::AST::Node>]
+    attr_reader :output
 
   private
 
@@ -47,10 +27,11 @@ def self.handle(*types)
     # @param [#call(node)] block
     #
     # @return [undefined]
-    def initialize(input, parent, block)
-      @input, @parent, @block = input, parent, block
-      @seen = Set.new
-      guard(input)
+    def initialize(_input, _parent = nil)
+      super
+
+      @output = Set.new
+
       dispatch
     end
 
@@ -60,16 +41,7 @@ def initialize(input, parent, block)
     #
     # @return [Boolean]
     def new?(object)
-      !@seen.include?(object)
-    end
-
-    # Add object to guarded values
-    #
-    # @param [Object] object
-    #
-    # @return [undefined]
-    def guard(object)
-      @seen << object
+      !object.eql?(input)
     end
 
     # Dispatch node generations
@@ -85,26 +57,14 @@ def guard(object)
     def emit(object)
       return unless new?(object)
 
-      guard(object)
-
-      emit!(object)
-    end
-
-    # Call block with node
-    #
-    # @param [Parser::AST::Node] node
-    #
-    # @return [self]
-    def emit!(node)
-      @block.call(node)
-      self
+      output << object
     end
 
     # Run input with mutator
     #
     # @return [undefined]
     def run(mutator)
-      mutator.new(input, self, method(:emit))
+      mutator.call(input).each(&method(:emit))
     end
 
     # Shortcut to create a new unfrozen duplicate of input

lib/mutant/mutator/node.rb

@@ -20,11 +20,11 @@ class Node < self
       def self.define_named_child(name, index)
         super
 
-        define_method("emit_#{name}_mutations") do |&block|
+        define_method(:"emit_#{name}_mutations") do |&block|
           mutate_child(index, &block)
         end
 
-        define_method("emit_#{name}") do |node|
+        define_method(:"emit_#{name}") do |node|
           emit_child_update(index, node)
         end
       end
@@ -56,10 +56,9 @@ def children
       # @return [undefined]
       #
       # rubocop:disable RedundantBlockCall - its not redundant here
-      def mutate_child(index, mutator = Mutator, &block)
+      def mutate_child(index, &block)
         block ||= TAUTOLOGY
-        child = children.at(index)
-        mutator.each(child, self) do |mutation|
+        REGISTRY.call(children.fetch(index), self).each do |mutation|
           next unless block.call(mutation)
           emit_child_update(index, mutation)
         end
@@ -119,17 +118,6 @@ def emit_nil
         emit(N_NIL) unless asgn_left?
       end
 
-      # Emit values
-      #
-      # @param [Array<Object>] values
-      #
-      # @return [undefined]
-      def emit_values(values)
-        values.each do |value|
-          emit_type(value)
-        end
-      end
-
       # Parent node
       #
       # @return [Parser::AST::Node] node
@@ -165,9 +153,17 @@ def asgn_left?
       #
       # @return [Enumerable<Fixnum>]
       def children_indices(range)
-        range_end = range.end
-        last_index = range_end >= 0 ? range_end : children.length + range_end
-        range.begin.upto(last_index)
+        range.begin.upto(children.length + range.end)
+      end
+
+      # Emit single child mutation
+      #
+      # @return [undefined]
+      def mutate_single_child
+        children.each_with_index do |child, index|
+          mutate_child(index)
+          yield child, index unless children.one?
+        end
       end
 
     end # Node

lib/mutant/mutator/node/arguments.rb

@@ -22,7 +22,7 @@ def dispatch
         # @return [undefined]
         def emit_argument_presence
           emit_type
-          Mutator::Util::Array::Presence.each(children, self) do |children|
+          Util::Array::Presence.call(children).each do |children|
             emit_type(*children)
           end
         end
@@ -32,7 +32,7 @@ def emit_argument_presence
         # @return [undefined]
         def emit_argument_mutations
           children.each_with_index do |child, index|
-            Mutator.each(child) do |mutant|
+            REGISTRY.call(child).each do |mutant|
               next if invalid_argument_replacement?(mutant, index)
               emit_child_update(index, mutant)
             end
@@ -45,11 +45,7 @@ def emit_argument_mutations
         #
         # @return [Boolean]
         def invalid_argument_replacement?(mutant, index)
-          original = children.fetch(index)
-
-          n_optarg?(original) &&
-          n_arg?(mutant)      &&
-          children[0...index].any?(&method(:n_optarg?))
+          n_arg?(mutant) && children[0...index].any?(&method(:n_optarg?))
         end
 
         # Emit mlhs expansions
@@ -59,7 +55,7 @@ def emit_mlhs_expansion
           mlhs_childs_with_index.each do |child, index|
             dup_children = children.dup
             dup_children.delete_at(index)
-            dup_children.insert(index, *child.children)
+            dup_children.insert(index, *child)
             emit_type(*dup_children)
           end
         end

lib/mutant/mutator/node/begin.rb

@@ -13,23 +13,10 @@ class Begin < self
         #
         # @return [undefined]
         def dispatch
-          Util::Array.each(children, self, &method(:emit_child_subset))
-          children.each_with_index do |child, index|
-            mutate_child(index)
-            emit(child) unless children.eql?([child])
+          mutate_single_child do |child|
+            emit(child)
           end
         end
-
-        # Emit child subset
-        #
-        # @param [Array<Parser::AST::Node>] children
-        #
-        # @return [undefined]
-        def emit_child_subset(children)
-          return if children.length < 2
-          emit_type(*children)
-        end
-
       end # Block
     end # Node
   end # Mutator

lib/mutant/mutator/node/break.rb

@@ -13,7 +13,7 @@ class Break < Generic
         #
         # @return [undefined]
         def dispatch
-          super
+          super()
           emit_singletons
           children.each_index(&method(:delete_child))
         end

lib/mutant/mutator/node/dstr.rb

@@ -13,7 +13,7 @@ class Dstr < Generic
         #
         # @return [undefined]
         def dispatch
-          super
+          super()
           emit_singletons
         end
 

lib/mutant/mutator/node/dsym.rb

@@ -13,7 +13,7 @@ class Dsym < Generic
         #
         # @return [undefined]
         def dispatch
-          super
+          super()
           emit_singletons
         end
 

lib/mutant/mutator/node/generic.rb

@@ -8,9 +8,9 @@ class Generic < self
         # These nodes still need a dedicated mutator,
         # your contribution is that close!
         handle(
-          :ensure, :redo, :regopt, :retry, :arg_expr,
+          :ensure, :redo, :regopt, :retry, :arg_expr, :blockarg,
           :kwrestarg, :kwoptarg, :kwarg, :undef, :module, :empty,
-          :alias, :for, :xstr, :back_ref, :class,
+          :alias, :for, :xstr, :back_ref, :class, :restarg,
           :sclass, :match_with_lvasgn, :while_post,
           :until_post, :preexe, :postexe, :iflipflop, :eflipflop, :kwsplat,
           :shadowarg, :rational, :complex, :__FILE__, :__LINE__

lib/mutant/mutator/node/kwbegin.rb

@@ -13,7 +13,7 @@ class Kwbegin < Generic
         #
         # @return [undefined]
         def dispatch
-          super
+          super()
           emit_singletons
         end
 

lib/mutant/mutator/node/literal.rb

@@ -4,6 +4,15 @@ class Node
       # Abstract mutator for literal AST nodes
       class Literal < self
         include AbstractType
+
+      private
+
+        # Emit values
+        #
+        # @return [undefined]
+        def emit_values
+          values.each(&method(:emit_type))
+        end
       end # Literal
     end # Node
   end # Mutator

lib/mutant/mutator/node/literal/fixnum.rb

@@ -14,7 +14,7 @@ class Fixnum < self
           # @return [undefined]
           def dispatch
             emit_singletons
-            emit_values(values)
+            emit_values
           end
 
           # Values to mutate to