Fix generator for mailer

Author: psantos10

lib/generators/rspec/mailer/mailer_generator.rb

@@ -8,7 +8,8 @@ class MailerGenerator < Base
       argument :actions, type: :array, default: [], banner: "method method"
 
       def generate_mailer_spec
-        template "mailer_spec.rb", target_path('mailers', class_path, "#{file_name}_spec.rb")
+        file_suffix = file_name.end_with?('mailer') ? 'spec.rb' : 'mailer_spec.rb'
+        template "mailer_spec.rb", target_path('mailers', class_path, [file_name, file_suffix].join('_'))
       end
 
       def generate_fixtures_files
@@ -21,7 +22,8 @@ def generate_fixtures_files
       def generate_preview_files
         return unless RSpec::Rails::FeatureCheck.has_action_mailer_preview?
 
-        template "preview.rb", target_path("mailers/previews", class_path, "#{file_name}_preview.rb")
+        file_suffix = file_name.end_with?('mailer') ? 'preview.rb' : 'mailer_preview.rb'
+        template "preview.rb", target_path("mailers/previews", class_path, [file_name, file_suffix].join('_'))
       end
     end
   end

lib/generators/rspec/mailer/templates/preview.rb

@@ -1,6 +1,6 @@
 <% module_namespacing do -%>
 # Preview all emails at http://localhost:3000/rails/mailers/<%= file_path %>
-class <%= class_name %>Preview < ActionMailer::Preview
+class <%= class_name %><%= 'Mailer' unless class_name.end_with?('Mailer') %>Preview < ActionMailer::Preview
 <% actions.each do |action| -%>
 
   # Preview this email at http://localhost:3000/rails/mailers/<%= file_path %>/<%= action %>