Adding yaml as option for generator

New installations will get :yaml as it's default with openapi 3 as the
version. Old installations will have the key missing and will default
to :json with an easy upgrade path.

rswag-specs/lib/generators/rswag/specs/install/templates/swagger_helper.rb

@@ -13,8 +13,8 @@ RSpec.configure do |config|
   # document below. You can override this behavior by adding a swagger_doc tag to the
   # the root example_group in your specs, e.g. describe '...', swagger_doc: 'v2/swagger.json'
   config.swagger_docs = {
-    'v1/swagger.json' => {
-      swagger: '2.0',
+    'v1/swagger.yaml' => {
+      openapi: '3.0.1',
       info: {
         title: 'API V1',
         version: 'v1'
@@ -22,4 +22,10 @@ RSpec.configure do |config|
       paths: {}
     }
   }
+
+  # Specify the format of the output Swagger file when running 'rswag:specs:swaggerize'.
+  # The swagger_docs configuration option has the filename including format in
+  # the key, this may want to be changed to avoid putting yaml in json files.
+  # Defaults to json. Accepts ':json' and ':yaml'.
+  config.swagger_format = :yaml
 end

rswag-specs/lib/rswag/specs.rb

@@ -12,6 +12,7 @@ module Rswag
       c.add_setting :swagger_root
       c.add_setting :swagger_docs
       c.add_setting :swagger_dry_run
+      c.add_setting :swagger_format
       c.extend ExampleGroupHelpers, type: :request
       c.include ExampleHelpers, type: :request
     end

rswag-specs/lib/rswag/specs/configuration.rb

@@ -31,6 +31,14 @@ module Rswag
         end
       end
 
+      def swagger_format
+        @swagger_format ||= begin
+          @rspec_config.swagger_format = :json if @rspec_config.swagger_format.nil? || @rspec_config.swagger_format.empty?
+          raise ConfigurationError, "Unknown swagger_format '#{@rspec_config.swagger_format}'" unless [:json, :yaml].include?(@rspec_config.swagger_format)
+          @rspec_config.swagger_format
+        end
+      end
+
       def get_swagger_doc(name)
         return swagger_docs.values.first if name.nil?
         raise ConfigurationError, "Unknown swagger_doc '#{name}'" unless swagger_docs[name]

rswag-specs/spec/rswag/specs/configuration_spec.rb

@@ -6,7 +6,9 @@ module Rswag
     RSpec.describe Configuration do
       subject { described_class.new(rspec_config) }
 
-      let(:rspec_config) { OpenStruct.new(swagger_root: swagger_root, swagger_docs: swagger_docs) }
+      let(:rspec_config) do
+        OpenStruct.new(swagger_root: swagger_root, swagger_docs: swagger_docs, swagger_format: swagger_format)
+      end
       let(:swagger_root) { 'foobar' }
       let(:swagger_docs) do
         {
@@ -14,6 +16,7 @@ module Rswag
           'v2/swagger.json' => { info: { title: 'v2' } }
         }
       end
+      let(:swagger_format) { :yaml }
 
       describe '#swagger_root' do
         let(:response) { subject.swagger_root }
@@ -46,6 +49,26 @@ module Rswag
         end
       end
 
+      describe '#swagger_format' do
+        let(:response) { subject.swagger_format }
+
+        context 'provided in rspec config' do
+          it { expect(response).to be_an_instance_of(Symbol) }
+        end
+
+        context 'unsupported format provided' do
+          let(:swagger_format) { :xml }
+
+          it { expect { response }.to raise_error ConfigurationError }
+        end
+
+        context 'not provided' do
+          let(:swagger_format) { nil }
+
+          it { expect(response).to eq(:json) }
+        end
+      end
+
       describe '#get_swagger_doc(tag=nil)' do
         let(:swagger_doc) { subject.get_swagger_doc(tag) }