Add mutator for yield nodes

lib/mutant.rb

@@ -74,6 +74,7 @@ require 'mutant/mutator/node/named_value/variable_assignment'
 require 'mutant/mutator/node/noop'
 require 'mutant/mutator/node/op_asgn'
 require 'mutant/mutator/node/while'
+require 'mutant/mutator/node/yield'
 require 'mutant/mutator/node/super'
 require 'mutant/mutator/node/zsuper'
 require 'mutant/mutator/node/restarg'

lib/mutant/mutator/node/generic.rb

@@ -11,7 +11,7 @@ module Mutant
         # your contribution is that close!
         handle(
           :next, :break, :ensure,
-          :yield, :rescue, :redo, :defined?,
+          :rescue, :redo, :defined?,
           :regopt, :resbody, :retry, :arg_expr,
           :kwrestarg, :kwoptarg, :kwarg, :undef, :module, :empty,
           :alias, :for, :xstr, :back_ref, :class,

lib/mutant/mutator/node/yield.rb

@@ -0,0 +1,29 @@
+# encoding: utf-8
+
+module Mutant
+  class Mutator
+    class Node
+
+      # Yield mutator
+      class Yield < Generic
+
+        handle(:yield)
+
+      private
+
+        # Emit mutations
+        #
+        # @return [undefined]
+        #
+        # @api private
+        #
+        def dispatch
+          super
+          children.each_index(&method(:delete_child))
+          emit_nil
+        end
+
+      end # Yield
+    end # Node
+  end # Mutator
+end # Mutant

spec/unit/mutant/mutator/node/yield/mutation_spec.rb

@@ -9,6 +9,8 @@ describe Mutant::Mutator::Node::Generic, 'yield' do
     mutations = []
     mutations << 'yield false'
     mutations << 'yield nil'
+    mutations << 'yield'
+    mutations << 'nil'
   end
 
   it_should_behave_like 'a mutator'