Add #features to adapter wrapper.

lib/flipper/adapter.rb

@@ -101,6 +101,10 @@ def eql?(other)
     end
     alias :== :eql?
 
+    def features
+      set_members('features')
+    end
+
     private
 
     def cache(key)

spec/flipper/adapter_spec.rb

@@ -280,4 +280,25 @@
       (subject == described_class.new(adapter)).should be_true
     end
   end
+
+  describe "#features" do
+    context "with no features enabled/disabled" do
+      it "defaults to empty set" do
+        subject.features.should eq(Set.new)
+      end
+    end
+
+    context "with features enabled and disabled" do
+      before do
+        subject.set_add('features', 'stats')
+        subject.set_add('features', 'cache')
+        subject.set_add('features', 'search')
+      end
+
+      it "returns set of feature names" do
+        subject.features.should be_instance_of(Set)
+        subject.features.sort.should eq(['cache', 'search', 'stats'])
+      end
+    end
+  end
 end