Extract step_match caching to a decorator.

I've left the creation of th cache explicit at construction for the
moment. There may be a better api we can use, but wanted to wait to see
if we can reuse it in plugins first.

lib/cucumber/runtime.rb

@@ -46,7 +46,7 @@ class Runtime
 
     def initialize(configuration = Configuration.default)
       @configuration = Configuration.parse(configuration)
-      @support_code = SupportCode.new(self, @configuration)
+      @support_code = SupportCode::CachesStepMatch.new SupportCode.new(self, @configuration)
       @results = Formatter::LegacyApi::Results.new
     end
 

lib/cucumber/runtime/support_code.rb

@@ -148,25 +148,16 @@ def find_around_hooks(test_case)
         end
       end
 
-      def step_match(step_name, name_to_report=nil) #:nodoc:
-        @match_cache ||= {}
-
-        match = @match_cache[[step_name, name_to_report]]
-        return match if match
-
-        @match_cache[[step_name, name_to_report]] = step_match_without_cache(step_name, name_to_report)
-      end
-
-      private
-
-      def step_match_without_cache(step_name, name_to_report=nil)
+      def step_match(step_name, name_to_report=nil)
         matches = matches(step_name, name_to_report)
         raise Undefined.new(step_name) if matches.empty?
         matches = best_matches(step_name, matches) if matches.size > 1 && guess_step_matches?
         raise Ambiguous.new(step_name, matches, guess_step_matches?) if matches.size > 1
         matches[0]
       end
 
+      private
+
       def guess_step_matches?
         @configuration.guess?
       end
@@ -200,6 +191,17 @@ def log
         Cucumber.logger
       end
 
+      require 'delegate'
+      class CachesStepMatch < SimpleDelegator
+        def step_match(step_name, name_to_report=nil) #:nodoc:
+          @match_cache ||= {}
+
+          match = @match_cache[[step_name, name_to_report]]
+          return match if match
+
+          @match_cache[[step_name, name_to_report]] = super(step_name, name_to_report)
+        end
+      end
     end
   end
 end

lib/cucumber/step_definitions.rb

@@ -2,7 +2,7 @@ module Cucumber
   class StepDefinitions
     def initialize(configuration = Configuration.default)
       configuration = Configuration.parse(configuration)
-      @support_code = Runtime::SupportCode.new(nil, configuration)
+      @support_code = Runtime::SupportCode::CachesStepMatch.new Runtime::SupportCode.new(nil, configuration)
       @support_code.load_files_from_paths(configuration.autoload_code_paths)
     end
 

spec/cucumber/runtime/support_code_spec.rb

@@ -19,15 +19,19 @@ module Cucumber
       expect(format).to eq "it [snows] in [april]"
     end
 
-    it "caches step match results" do
-      dsl.Given(/it (.*) in (.*)/) { |what, month| }
+    context 'caching' do
+      let(:cached) { Runtime::SupportCode::CachesStepMatch.new(subject) }
+
+      it "caches step match results" do
+        dsl.Given(/it (.*) in (.*)/) { |what, month| }
 
-      step_match = subject.step_match("it snows in april")
+        step_match = cached.step_match("it snows in april")
 
-      expect(@rb).not_to receive(:step_matches)
-      second_step_match = subject.step_match("it snows in april")
+        expect(@rb).not_to receive(:step_matches)
+        second_step_match = cached.step_match("it snows in april")
 
-      expect(step_match).to equal(second_step_match)
+        expect(step_match).to equal(second_step_match)
+      end
     end
 
     describe "resolving step defintion matches" do