Add class mutator

Fixes #619

lib/mutant.rb

@@ -117,6 +117,7 @@ require 'mutant/mutator/node/send/conditional'
 require 'mutant/mutator/node/send/attribute_assignment'
 require 'mutant/mutator/node/send/index'
 require 'mutant/mutator/node/when'
+require 'mutant/mutator/node/class'
 require 'mutant/mutator/node/define'
 require 'mutant/mutator/node/mlhs'
 require 'mutant/mutator/node/nthref'

lib/mutant/mutator/node/class.rb

@@ -0,0 +1,21 @@
+module Mutant
+  class Mutator
+    class Node
+      # Namespace for class mutations
+      class Class < self
+        handle :class
+
+        children :klass, :parent, :body
+
+      private
+
+        # Emit mutations only for class body
+        #
+        # @return [undefined]
+        def dispatch
+          emit_body_mutations if body
+        end
+      end # Class
+    end # Node
+  end # Mutator
+end # Mutant

lib/mutant/mutator/node/generic.rb

@@ -10,7 +10,7 @@ module Mutant
         handle(
           :ensure, :redo, :retry, :arg_expr, :blockarg,
           :kwrestarg, :undef, :module, :empty,
-          :alias, :for, :xstr, :back_ref, :class, :restarg,
+          :alias, :for, :xstr, :back_ref, :restarg,
           :sclass, :match_with_lvasgn, :while_post,
           :until_post, :preexe, :postexe, :iflipflop, :eflipflop, :kwsplat,
           :shadowarg, :rational, :complex, :__FILE__, :__LINE__

meta/class.rb

@@ -0,0 +1,10 @@
+Mutant::Meta::Example.add :class do
+  source 'class Foo; bar; end'
+
+  mutation 'class Foo; nil; end'
+  mutation 'class Foo; self; end'
+end
+
+Mutant::Meta::Example.add :class do
+  source 'class Foo; end'
+end