Add constant assignment mutator

lib/mutant.rb

@@ -58,6 +58,7 @@ require 'mutant/mutator/node/argument'
 require 'mutant/mutator/node/arguments'
 require 'mutant/mutator/node/begin'
 require 'mutant/mutator/node/named_value/access'
+require 'mutant/mutator/node/named_value/constant_assignment'
 require 'mutant/mutator/node/named_value/variable_assignment'
 require 'mutant/mutator/node/while'
 require 'mutant/mutator/node/super'

lib/mutant/mutator/node/generic.rb

@@ -14,7 +14,7 @@ module Mutant
           :next, :break, :match, :ensure,
           :dstr, :dsym, :yield, :rescue, :redo, :defined?,
           :blockarg, :block_pass, :op_asgn, :and_asgn,
-          :regopt, :restarg, :casgn, :resbody, :retry, :arg_expr,
+          :regopt, :restarg, :resbody, :retry, :arg_expr,
           :kwrestarg, :kwoptarg, :kwarg, :undef, :module, :cbase, :empty,
           :alias, :for, :xstr, :back_ref, :nth_ref, :class,
           :sclass, :match_with_lvasgn, :match_current_line, :or_asgn, :kwbegin

lib/mutant/mutator/node/named_value/constant_assignment.rb

@@ -0,0 +1,42 @@
+module Mutant
+  class Mutator
+    class Node
+      module NamedValue
+
+        # Mutation emitter to handle constant assignment nodes
+        class ConstantAssignment < Node
+
+          children :cbase, :name, :value
+
+          handle :casgn
+
+        private
+
+          # Perform dispatch
+          #
+          # @return [undefined]
+          #
+          # @api private
+          #
+          def dispatch
+            mutate_name
+            emit_value_mutations if value
+          end
+
+          # Emit name mutations
+          #
+          # @return [undefined]
+          #
+          # @api private
+          #
+          def mutate_name
+            Mutator::Util::Symbol.each(name, self) do |name|
+              emit_name(name.upcase)
+            end
+          end
+
+        end # ConstantAssignment
+      end # NamedValue
+    end # Node
+  end # Mutator
+end # Mutant

spec/unit/mutant/mutator/node/named_value/constant_assignment/mutation_spec.rb

@@ -0,0 +1,20 @@
+require 'spec_helper'
+
+describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
+
+  before do
+    Mutant::Random.stub(:hex_string => :RANDOM)
+  end
+
+  let(:source) { 'A = true' }
+
+  let(:mutations) do
+    mutations = []
+
+    mutations << 'SRANDOM = true'
+    mutations << 'A = false'
+    mutations << 'A = nil'
+  end
+
+  it_should_behave_like 'a mutator'
+end