removed rails 5.0 check for mailer preview generator (rspec#2037)

* removed rails 5.0 check for mailer preview generator

* Add test fot mailer generator

Author: koheisg

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

@@ -5,7 +5,7 @@ class <%= class_name %>Preview < ActionMailer::Preview
 
   # Preview this email at http://localhost:3000/rails/mailers/<%= file_path %>/<%= action %>
   def <%= action %>
-    <%= class_name %><%= Rails.version.to_f >= 5.0 ? "Mailer" : "" %>.<%= action %>
+    <%= Rails.version.to_f >= 5.0 ? class_name.sub(/(Mailer)?$/, 'Mailer') : class_name %>.<%= action %>
   end
 <% end -%>
 

spec/generators/rspec/mailer/mailer_generator_spec.rb

@@ -56,6 +56,16 @@
     it { is_expected.to exist }
     it { is_expected.to contain(/class PostsPreview < ActionMailer::Preview/) }
     it { is_expected.to contain(/def index/) }
+    if Rails.version.to_f >= 5.0
+      it { is_expected.to contain(/PostsMailer.index/) }
+    else
+      it { is_expected.to contain(/Posts.index/) }
+    end
     it { is_expected.to contain(/def show/) }
+    if Rails.version.to_f >= 5.0
+      it { is_expected.to contain(/PostsMailer.show/) }
+    else
+      it { is_expected.to contain(/Posts.show/) }
+    end
   end
 end