Fix Proc with arity one in param values (ruby-grape#613)

Author: timothysu

CHANGELOG.md

@@ -3,6 +3,7 @@
 #### Features
 
 * Your contribution here.
+* [#613](https://github.com/ruby-grape/grape-swagger/pull/613): Fix Proc with arity one in param values - [@timothysu](https://github.com/timothysu).
 
 #### Fixes
 

lib/grape-swagger/doc_methods/parse_params.rb

@@ -101,7 +101,7 @@ def param_type(value_type)
         def parse_enum_or_range_values(values)
           case values
           when Proc
-            parse_enum_or_range_values(values.call)
+            parse_enum_or_range_values(values.call) if values.parameters.empty?
           when Range
             parse_range_values(values) if values.first.is_a?(Integer)
           else

spec/lib/parse_params_spec.rb

@@ -47,6 +47,14 @@
           expect(parsed_range).to eql(enum: %w[a b c])
         end
       end
+
+      describe 'with arity one' do
+        let(:values) { proc { |v| v < 25 } }
+        specify do
+          parsed_range = subject.send(:parse_enum_or_range_values, values)
+          expect(parsed_range).to be_nil
+        end
+      end
     end
 
     describe 'values as Array -> enums' do