Write the files using specified format

rswag-specs/lib/rswag/specs/swagger_formatter.rb

@@ -37,7 +37,7 @@ module Rswag
           FileUtils.mkdir_p dirname unless File.exists?(dirname)
 
           File.open(file_path, 'w') do |file|
-            file.write(JSON.pretty_generate(doc))
+            file.write(pretty_generate(doc))
           end
 
           @output.puts "Swagger doc generated at #{file_path}"
@@ -46,6 +46,14 @@ module Rswag
 
       private
 
+      def pretty_generate(doc)
+        if @config.swagger_format == :yaml
+          YAML.dump(doc)
+        else # config errors are thrown in 'def swagger_format', no throw needed here
+          JSON.pretty_generate(doc)
+        end
+      end
+
       def metadata_to_swagger(metadata)
         response_code = metadata[:response][:code]
         response = metadata[:response].reject { |k,v| k == :code }

rswag-specs/spec/rswag/specs/swagger_formatter_spec.rb

@@ -53,14 +53,28 @@ module Rswag
             'v1/swagger.json' => { info: { version: 'v1' } },
             'v2/swagger.json' => { info: { version: 'v2' } }
           )
+          allow(config).to receive(:swagger_format).and_return(swagger_format)
           subject.stop(notification)
         end
 
         let(:notification) { double('notification') }
+        context 'with default format' do
+          let(:swagger_format) { :json }
 
-        it 'writes the swagger_doc(s) to file' do
-          expect(File).to exist("#{swagger_root}/v1/swagger.json")
-          expect(File).to exist("#{swagger_root}/v2/swagger.json")
+          it 'writes the swagger_doc(s) to file' do
+            expect(File).to exist("#{swagger_root}/v1/swagger.json")
+            expect(File).to exist("#{swagger_root}/v2/swagger.json")
+            expect { JSON.parse(File.read("#{swagger_root}/v2/swagger.json")) }.not_to raise_error
+          end
+        end
+
+        context 'with yaml format' do
+          let(:swagger_format) { :yaml }
+
+          it 'writes the swagger_doc(s) as yaml' do
+            expect(File).to exist("#{swagger_root}/v1/swagger.json")
+            expect { JSON.parse(File.read("#{swagger_root}/v1/swagger.json")) }.to raise_error(JSON::ParserError)
+          end
         end
 
         after do