Better error message on wrong API usage

Author: sobrinho

lib/abstract_builder.rb

@@ -97,7 +97,7 @@ def method_missing(*args, &block)
               comment_builder.content comment.content
             end
 
-        Received #{args.length - 1} argument#{'s' if args.length > 2} #{block ? "with a block" : "without a block"}.
+        Received `#{args[0]}' with #{args.length - 1} argument#{'s' if args.length > 2} #{block ? "with a block" : "without a block"}.
       EOF
     end
   end

spec/abstract_builder_spec.rb

@@ -240,7 +240,7 @@
         subject.people people, invalid_option: true do |builder, person|
           builder.name person.name
         end
-      }.to raise_error(ArgumentError, /Expected 1 argument without a block, 0 arguments with a block or 1 argument with a block.+Received 2 arguments with a block./m)
+      }.to raise_error(ArgumentError, /Expected 1 argument without a block, 0 arguments with a block or 1 argument with a block.+Received `people' with 2 arguments with a block./m)
     end
   end