Reduce public interface of Subject

lib/mutant/mutation.rb

@@ -99,7 +99,7 @@ module Mutant
     # @api private
     #
     def root
-      subject.root(node)
+      subject.context.root(node)
     end
 
     # Evil mutation that should case mutations to fail tests

lib/mutant/subject.rb

@@ -88,18 +88,6 @@ module Mutant
     end
     memoize :source
 
-    # Return root AST for node
-    #
-    # @param [Parser::AST::Node] node
-    #
-    # @return [Parser::AST::Node]
-    #
-    # @api private
-    #
-    def root(node)
-      context.root(node)
-    end
-
     # Return match expression
     #
     # @return [Expression]

spec/unit/mutant/mutation_spec.rb

@@ -5,7 +5,8 @@ RSpec.describe Mutant::Mutation do
   end
 
   let(:object)           { TestMutation.new(mutation_subject, Mutant::AST::Nodes::N_NIL)                      }
-  let(:mutation_subject) { double('Subject', identification: 'subject', source: 'original') }
+  let(:mutation_subject) { double('Subject', identification: 'subject', context: context, source: 'original') }
+  let(:context)          { double('Context')                                                                  }
 
   describe '#code' do
     subject { object.code }
@@ -31,7 +32,7 @@ RSpec.describe Mutant::Mutation do
     before do
       expect(mutation_subject).to receive(:public?).ordered.and_return(true)
       expect(mutation_subject).to receive(:prepare).ordered
-      expect(mutation_subject).to receive(:root).ordered.with(s(:nil)).and_return(wrapped_node)
+      expect(context).to receive(:root).ordered.with(s(:nil)).and_return(wrapped_node)
       expect(Mutant::Loader::Eval).to receive(:call).ordered.with(wrapped_node, mutation_subject).and_return(nil)
     end