Fix Grape 3.2 compatibility: keyword args for desc and custom param types

.rubocop_todo.yml

@@ -6,6 +6,14 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
+# Offense count: 4
+# Configuration parameters: Severity.
+Style/OneClassPerFile:
+  Exclude:
+    - 'lib/grape-swagger.rb'
+    - 'spec/support/empty_model_parser.rb'
+    - 'spec/swagger_v2/guarded_endpoint_spec.rb'
+
 # Offense count: 1
 # Configuration parameters: Severity, Include.
 # Include: **/*.gemspec

CHANGELOG.md

@@ -6,7 +6,7 @@
 
 #### Fixes
 
-* Your contribution here.
+* [#977](https://github.com/ruby-grape/grape-swagger/issues/977): Pass keyword arguments to `desc` to fix deprecation warning from Grape - [@numbata](https://github.com/numbata).
 
 ### 2.1.4 (2026-02-02)
 

lib/grape-swagger/doc_methods.rb

@@ -93,7 +93,7 @@ def setup(options)
 
       setup_formatter(options[:format])
 
-      desc api_doc.delete(:desc), api_doc
+      desc api_doc.delete(:desc), **api_doc
 
       instance_eval(guard) unless guard.nil?
 
@@ -105,7 +105,7 @@ def setup(options)
           .output_path_definitions(target_class.combined_namespace_routes, self, target_class, options)
       end
 
-      desc specific_api_doc.delete(:desc), { params: specific_api_doc.delete(:params) || {}, **specific_api_doc }
+      desc specific_api_doc.delete(:desc), params: specific_api_doc.delete(:params) || {}, **specific_api_doc
 
       params do
         requires :name, type: String, desc: 'Resource name of mounted API'

spec/support/model_parsers/mock_parser.rb

@@ -72,7 +72,13 @@ class RecursiveModel < OpenStruct; end
       class DocumentedHashAndArrayModel < OpenStruct; end
 
       module NestedModule
-        class ApiResponse < OpenStruct; end
+        class ApiResponse < OpenStruct
+          # Grape 3.2+ requires unknown types to implement .parse (arity 1) to pass the
+          # Types.custom? check and avoid a dry-types lookup that would raise ArgumentError.
+          # The implementation is minimal because these tests exercise swagger doc generation
+          # only, not actual request coercion.
+          def self.parse(val) = val
+        end
       end
     end
   end

spec/support/model_parsers/representable_parser.rb

@@ -99,6 +99,11 @@ class ApiResponse < Representable::Decorator
 
           property :status, documentation: { type: String }
           property :error, documentation: { type: ::Entities::ApiError }
+
+          # Grape 3.2+ requires unknown types to implement .parse (arity 1) to pass the
+          # Types.custom? check. Representable::Decorator does not define parse, so we add
+          # a minimal pass-through sufficient for documentation-generation tests.
+          def self.parse(val) = val
         end
       end
 

spec/swagger_v2/params_example_spec.rb

@@ -11,7 +11,10 @@ def app
         params :common_params do
           requires :id, type: Integer, documentation: { example: 123 }
           optional :name, type: String, documentation: { example: 'Person' }
-          optional :obj, type: 'Object', documentation: { example: { 'foo' => 'bar' } }
+          # 'Object' is not a valid Grape coercion type; it is a swagger documentation-only hint.
+          # Grape 3.2+ rejects string type names in params blocks, so the type lives in
+          # documentation: where grape-swagger picks it up via ParseParams#call settings merge.
+          optional :obj, documentation: { type: 'Object', example: { 'foo' => 'bar' } }
         end
       end