Allow OpenAPI 3.0 array query parameter schema (rswag#317)

In OpenAPI 3.0, a query parameter can be specified like:

```
name: id
in: query
schema:
  type: array
  items:
    type: string
```
see: https://swagger.io/specification/#parameter-object

In order to support generating the correct OpenAPI 3.0 specification and
to still allow rswag specs to pass, this checks to see if `array` is
specified in the `type` of the parameter, or if it's specified in the
`schema: { type:` instead.

re: rswag#317

rswag-specs/lib/rswag/specs/request_factory.rb

@@ -111,14 +111,23 @@ def add_path(request, metadata, swagger_doc, parameters, example)
 
           parameters.select { |p| p[:in] == :query }.each_with_index do |p, i|
             path_template.concat(i.zero? ? '?' : '&')
-            path_template.concat(build_query_string_part(p, example.send(p[:name])))
+            path_template.concat(build_query_string_part(p, example.send(p[:name]), swagger_doc))
           end
         end
       end
 
-      def build_query_string_part(param, value)
+      def param_is_array?(param)
+        param[:type]&.to_sym == :array || param.dig(:schema, :type)&.to_sym == :array
+      end
+
+      def build_query_string_part(param, value, swagger_doc)
         name = param[:name]
-        return "#{name}=#{value}" unless param[:type].to_sym == :array
+
+        if doc_version(swagger_doc).start_with?('2')
+          return "#{name}=#{value}" unless param[:type].to_sym == :array
+        else # Openapi3
+          return "#{name}=#{value}" unless param_is_array?(param)
+        end
 
         case param[:collectionFormat]
         when :ssv

rswag-specs/spec/rswag/specs/request_factory_spec.rb

@@ -103,6 +103,52 @@ module Specs
           end
         end
 
+        context "'query' parameters of type 'array' by way of 'schema'" do
+          let(:swagger_doc) { { swagger: '3.0.3' } }
+
+          before do
+            metadata[:operation][:parameters] = [
+              { name: 'things', in: :query, schema: { type: :array }, collectionFormat: collection_format }
+            ]
+            allow(example).to receive(:things).and_return(['foo', 'bar'])
+          end
+
+          context 'collectionFormat = csv' do
+            let(:collection_format) { :csv }
+            it 'formats as comma separated values' do
+              expect(request[:path]).to eq('/blogs?things=foo,bar')
+            end
+          end
+
+          context 'collectionFormat = ssv' do
+            let(:collection_format) { :ssv }
+            it 'formats as space separated values' do
+              expect(request[:path]).to eq('/blogs?things=foo bar')
+            end
+          end
+
+          context 'collectionFormat = tsv' do
+            let(:collection_format) { :tsv }
+            it 'formats as tab separated values' do
+              expect(request[:path]).to eq('/blogs?things=foo\tbar')
+            end
+          end
+
+          context 'collectionFormat = pipes' do
+            let(:collection_format) { :pipes }
+            it 'formats as pipe separated values' do
+              expect(request[:path]).to eq('/blogs?things=foo|bar')
+            end
+          end
+
+          context 'collectionFormat = multi' do
+            let(:collection_format) { :multi }
+            it 'formats as multiple parameter instances' do
+              expect(request[:path]).to eq('/blogs?things=foo&things=bar')
+            end
+          end
+        end
+
         context "'header' parameters" do
           before do
             metadata[:operation][:parameters] = [{ name: 'Api-Key', in: :header, type: :string }]