Fix Set type with values

lib/grape/validations/params_scope.rb

@@ -490,7 +490,7 @@ def validate(type, options, attrs, doc, opts)
       def validate_value_coercion(coerce_type, *values_list)
         return unless coerce_type
 
-        coerce_type = coerce_type.first if coerce_type.is_a?(Array)
+        coerce_type = coerce_type.first if coerce_type.is_a?(Array) || coerce_type.is_a?(Set)
         values_list.each do |values|
           next if !values || values.is_a?(Proc)
 

spec/grape/validations/params_scope_spec.rb

@@ -189,6 +189,24 @@ def initialize(value)
     end
   end
 
+  context 'a set with coerce type explicitly given' do
+    context 'and the values are allowed' do
+      it 'does not raise an exception' do
+        expect do
+          subject.params { optional :numbers, type: Set[Integer], values: 0..2, default: 0..2 }
+        end.not_to raise_error
+      end
+    end
+
+    context 'and the values are not allowed' do
+      it 'raises exception' do
+        expect do
+          subject.params { optional :numbers, type: Set[Integer], values: %w[a b] }
+        end.to raise_error
+      end
+    end
+  end
+
   context 'with range values' do
     context "when left range endpoint isn't #kind_of? the type" do
       it 'raises exception' do