Handle 18 vs 19-mode differencies for if-statement

lib/mutant.rb

@@ -19,6 +19,18 @@ module Mutant
   def self.deep_clone(object)
     Marshal.load(Marshal.dump(object))
   end
+  
+  # Check for ruby-1.8 mode
+  #
+  # @return [true]
+  #   returns true if running under 1.8 mode
+  #
+  # @return [false]
+  #   returns false otherwise
+  #
+  def self.on_18?
+    RUBY_VERSION == '1.8.7'
+  end
 end
 
 require 'mutant/support/abstract'

lib/mutant/mutator/if_statement.rb

@@ -69,6 +69,10 @@ module Mutant
       # capture literal symbol.
       #
       def invert(node)
+        if Mutant.on_18?
+          return new(Rubinius::AST::Not,node)
+        end
+
         new_send(node,:'!')
       end
 

spec/unit/mutant/mutator/if_statement/mutation_spec.rb

@@ -10,7 +10,13 @@ describe Mutant::Mutator, 'if statement' do
     mutants << 'if condition; true; else false; end'
 
     # Invert condition
-    mutants << 'if !self.condition; true; else false; end'
+    if Mutant.on_18?
+      # Explicitly define ast as 18-mode does swap if and else on parsing when negation condition is 
+      # present in condition.
+      mutants << [:if, [:not, [:call, [:self], :condition, [:arglist]]], [:true], [:false]]
+    else
+      mutants << 'if !self.condition; true; else false; end'
+    end
 
     # Deleted else branch
     mutants << 'if self.condition; true end'