Improve internals of method matcher

* Fix name clash with Kernel#method
* Match full paths of node enabling next changes to fix exclusion of evaled methods from direct matches

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 1085
+total_score: 1094

lib/mutant/ast.rb

@@ -4,7 +4,8 @@ module Mutant
 
     # Walk all ast nodes
     #
-    # @param [Parser::AST::Node]
+    # @param [Parser::AST::Node] root
+    # @param [Array<Parser::AST::Node>] stack
     #
     # @yield [Parser::AST::Node]
     #   all nodes recursively including root
@@ -13,16 +14,19 @@ module Mutant
     #
     # @api private
     #
-    def self.walk(node, &block)
+    def self.walk(node, stack, &block)
       raise ArgumentError, 'block expected' unless block_given?
 
-      block.call(node)
+      block.call(node, stack)
       node.children.grep(Parser::AST::Node).each do |child|
-        walk(child, &block)
+        stack.push(child)
+        walk(child, stack, &block)
+        stack.pop
       end
 
       self
     end
+    private_class_method :walk
 
     # Find last node satisfying predicate (as block)
     #
@@ -39,13 +43,15 @@ module Mutant
     #
     # @api private
     #
-    def self.find_last(node, &predicate)
+    def self.find_last_path(node, &predicate)
       raise ArgumentError, 'block expected' unless block_given?
-      neddle = nil
-      walk(node) do |candidate|
-        neddle = candidate if predicate.call(candidate, &predicate)
+      path = []
+      walk(node, [node]) do |candidate, stack|
+        if predicate.call(candidate, &predicate)
+          path = stack.dup
+        end
       end
-      neddle
+      path
     end
 
   end # AST

lib/mutant/matcher/method.rb

@@ -2,7 +2,7 @@ module Mutant
   class Matcher
     # Matcher for subjects that are a specific method
     class Method < self
-      include Adamantium::Flat, Concord::Public.new(:env, :scope, :method)
+      include Adamantium::Flat, Concord::Public.new(:env, :scope, :target_method)
       include Equalizer.new(:identification)
 
       # Methods within rbx kernel directory are precompiled and their source
@@ -40,7 +40,7 @@ module Mutant
       def skip?
         location = source_location
         if location.nil? || BLACKLIST.match(location.first)
-          env.warn(format('%s does not have valid source location unable to emit matcher', method.inspect))
+          env.warn(format('%s does not have valid source location unable to emit matcher', target_method.inspect))
           true
         else
           false
@@ -54,7 +54,7 @@ module Mutant
       # @api private
       #
       def method_name
-        method.name
+        target_method.name
       end
 
       # Return context
@@ -104,7 +104,7 @@ module Mutant
       # @api private
       #
       def source_location
-        method.source_location
+        target_method.source_location
       end
 
       # Return subject
@@ -118,27 +118,22 @@ module Mutant
       # @api private
       #
       def subject
-        node = matched_node
+        node = matched_node_path.last
         return unless node
         self.class::SUBJECT_CLASS.new(env.config, context, node)
       end
       memoize :subject
 
-      # Return matched node
+      # Return matched node path
       #
-      # @return [Parser::AST::Node]
-      #   if node could be found
-      #
-      # @return [nil]
-      #   otherwise
+      # @return [Array<Parser::AST::Node>]
       #
       # @api private
       #
-      def matched_node
-        AST.find_last(ast) do |node|
-          match?(node)
-        end
+      def matched_node_path
+        AST.find_last_path(ast, &method(:match?))
       end
+      memoize :matched_node_path
 
     end # Method
   end # Matcher

lib/mutant/matcher/method/instance.rb

@@ -15,10 +15,10 @@ module Mutant
         #
         # @api private
         #
-        def self.build(env, scope, method)
-          name = method.name
+        def self.build(env, scope, target_method)
+          name = target_method.name
           if scope.ancestors.include?(::Memoizable) && scope.memoized?(name)
-            return Memoized.new(env, scope, method)
+            return Memoized.new(env, scope, target_method)
           end
           super
         end
@@ -68,7 +68,7 @@ module Mutant
           # @api private
           #
           def source_location
-            scope.unmemoized_instance_method(method.name).source_location
+            scope.unmemoized_instance_method(method_name).source_location
           end
 
         end # Memoized

spec/unit/mutant/ast_spec.rb

@@ -0,0 +1,38 @@
+RSpec.describe Mutant::AST do
+  let(:object) { described_class }
+
+  describe '.find_last_path' do
+    subject { object.find_last_path(root, &block) }
+
+    let(:root)    { s(:root, parent)             }
+    let(:child_a) { s(:child_a)                  }
+    let(:child_b) { s(:child_b)                  }
+    let(:parent)  { s(:parent, child_a, child_b) }
+
+    def path
+      subject.map(&:type)
+    end
+
+    context 'when no node matches' do
+      let(:block) { ->(_) { false } }
+
+      it { should eql([]) }
+    end
+
+    context 'when one node matches' do
+      let(:block) { ->(node) { node.equal?(child_a) } }
+
+      it 'returns the full path' do
+        expect(path).to eql([:root, :parent, :child_a])
+      end
+    end
+
+    context 'when two nodes match' do
+      let(:block) { ->(node) { node.equal?(child_a) || node.equal?(child_b) } }
+
+      it 'returns the last full path' do
+        expect(path).to eql([:root, :parent, :child_b])
+      end
+    end
+  end
+end