Fix value of enum to be Array

Author: takahashim

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 #### Fixes
 
+* [#850](https://github.com/ruby-grape/grape-swagger/pull/850): Fix value of `enum` to be `Array` - [@takahashim](https://github.com/takahashim)
 * Your contribution here.
 
 

UPGRADING.md

@@ -3,6 +3,7 @@
 ### Upgrading to >= 1.4.2
 
 - `additionalProperties` has been deprecated and will be removed in a future version of `grape-swagger`. It has been replaced with `additional_properties`.
+- The value of the `enum` attribute is now always an Array. If it has only one value, it will be a one-element Array.
 
 ### Upgrading to >= 1.4.0
 

lib/grape-swagger/doc_methods/parse_params.rb

@@ -163,8 +163,10 @@ def parse_enum_or_range_values(values)
             parse_enum_or_range_values(values.call) if values.parameters.empty?
           when Range
             parse_range_values(values) if values.first.is_a?(Integer)
+          when Array
+            { enum: values }
           else
-            { enum: values } if values
+            { enum: [values] } if values
           end
         end
 

spec/swagger_v2/param_values_spec.rb

@@ -141,7 +141,7 @@ def first_parameter_info(request)
         'name' => 'letter',
         'type' => 'string',
         'required' => true,
-        'enum' => 'string'
+        'enum' => %w[string]
       }]
     end
   end