fixes #186: helpers should allow multiple calls with modules and blocks

lib/grape/api.rb

@@ -208,9 +208,14 @@ def represent(model_class, options)
       #         end
       #       end
       #     end
-      def helpers(mod = nil, &block)
-        if block_given? || mod
-          mod ||= settings.peek[:helpers] || Module.new
+      def helpers(new_mod = nil, &block)
+        if block_given? || new_mod
+          mod = settings.peek[:helpers] || Module.new
+          if new_mod
+            mod.class_eval do
+              include new_mod
+            end
+          end
           mod.class_eval &block if block_given?
           set(:helpers, mod)
         else

spec/grape/api_spec.rb

@@ -575,6 +575,28 @@ def hello
       get '/howdy'
       last_response.body.should eql 'Hello, world.'
     end
+
+    it 'should allow multiple calls with modules and blocks' do
+      subject.helpers Module.new do
+        def one
+          1
+        end
+      end
+      subject.helpers Module.new do
+        def two
+          2
+        end
+      end
+      subject.helpers do
+        def three
+          3
+        end
+      end
+      subject.get 'howdy' do
+        [one, two, three]
+      end
+      lambda{get '/howdy'}.should_not raise_error
+    end
   end
 
   describe '.scope' do