hide the real name of the plain format

lib/api/decorators/formattable.rb

@@ -41,7 +41,7 @@ module API
 
       property :format,
                exec_context: :decorator,
-               getter: -> (*) { @format == '' ? 'plain' : @format },
+               getter: -> (*) { @format },
                writable: false,
                render_nil: true
       property :raw,

lib/api/v3/render/render_api.rb

@@ -53,7 +53,7 @@ module API
             end
 
             def check_format(format)
-              supported_formats = [''] # we always support no formatting (aka 'plain')
+              supported_formats = ['plain']
               supported_formats += Array(Redmine::WikiFormatting.format_names)
               unless supported_formats.include?(format)
                 fail ::API::Errors::NotFound, I18n.t('api_v3.errors.code_404')
@@ -108,7 +108,6 @@ module API
           route_param :render_format do
             before do
               @format = params[:render_format]
-              @format = '' if @format == 'plain' # 'plain' is called '' internally
             end
 
             post do

lib/api/v3/utilities/path_helper.rb

@@ -92,7 +92,7 @@ module API
 
           def self.render_markup(format: nil, link: nil)
             format = format || Setting.text_formatting
-            format = 'plain' if format == ''
+            format = 'plain' if format == '' # Setting will return '' for plain
 
             path = "#{root}/render/#{format}"
             path += "?#{link}" if link

lib/api/v3/versions/version_representer.rb

@@ -56,7 +56,7 @@ module API
                  getter: -> (*) {
                    ::API::Decorators::Formattable.new(represented.description,
                                                      object: represented,
-                                                     format: '')
+                                                     format: 'plain')
                  },
                  render_nil: true
 

lib/open_project/text_formatting.rb

@@ -82,7 +82,9 @@ module OpenProject
       project = options[:project] || @project || (obj && obj.respond_to?(:project) ? obj.project : nil)
       only_path = options.delete(:only_path) == false ? false : true
 
-      format = options[:format] || Setting.text_formatting
+      # offer 'plain' as readable version for 'no formatting' to callers
+      options_format = options[:format] == 'plain' ? '' : options[:format]
+      format = options_format || Setting.text_formatting
       text = Redmine::WikiFormatting.to_html(format, text,
                                              object: obj,
                                              attribute: attr,

spec/lib/api/decorators/formattable_spec.rb

@@ -49,7 +49,7 @@ describe ::API::Decorators::Formattable do
   end
 
   context 'format specified explicitly' do
-    subject { described_class.new(represented, format: '').to_json }
+    subject { described_class.new(represented, format: 'plain').to_json }
 
     it 'should indicate the explicit format' do
       is_expected.to be_json_eql('plain'.to_json).at_path('format')

spec/lib/open_project/text_formatting_spec.rb

@@ -513,7 +513,7 @@ EXPECTED
         end
 
         it 'uses format of options, if specified' do
-          expect(format_text('*Stars!*', format: '')).to eq('<p>*Stars!*</p>')
+          expect(format_text('*Stars!*', format: 'plain')).to eq('<p>*Stars!*</p>')
         end
       end
     end