Fix ActionMailer asset host in production. (#1044)

* Fix ActionMailer asset host in production (George)

This change was originally made in a suspenders-based app to fix a problem
we were having with images not rendering in emails. This commit replicates
the fix upstream for future suspenders users.

The change fixes image URLs in emails by adding a protocol to the
ActionMailer asset_host setting.

While the setting is called "host", based on the examples in the Rails
documentation, it could be more accurately described as a "URL-prefix" --
all of the examples include a protocol as well as a host.

Prior to this change, image URLs were generated in emails from production
environments with a protocol-relative URL (e.g. //example.com/image.png),
and were not rendering correctly in the various mail clients we tested.

* Fix regex that removes comment lines from Rails config files (Thiago)

That regex was causing the build to fail. The reason is that, when
generating a new Suspenders app, it removed the new asset host config
option introduced by George that contains a non-comment hashtag (#)
character.

Also, it was silently removing other lines of code that were being
confused as Ruby comments just because they had hashtag characters
somewhere (#) within them. Therefore, we are also fixing a bug here.

Unfortunately, the regex is a simplistic approach because it does not
factor in all possible Ruby comments. The only reliable way to remove
comments involves some AST parsing in order to reliably detect
comments and also preserve the general layout of the config files
without aggressively removing blank lines.

NOTE: The regex is buggy and may remove, for example, lines inside
heredoc strings starting with a # character, among others. Thankfully,
the config files we're dealing with here don't have such edge cases.

Co-authored-by: Thiago A. Silva <[email protected]>

lib/suspenders/app_builder.rb

@@ -168,10 +168,12 @@ def configure_action_mailer
       action_mailer_host "test", %("www.example.com")
       action_mailer_asset_host "test", %("http://www.example.com")
       action_mailer_host "production", %{ENV.fetch("APPLICATION_HOST")}
+      # rubocop:disable Lint/InterpolationCheck
       action_mailer_asset_host(
         "production",
-        %{ENV.fetch("ASSET_HOST", ENV.fetch("APPLICATION_HOST"))}
+        %q{"https://#{ENV.fetch("ASSET_HOST", ENV.fetch("APPLICATION_HOST"))}"}
       )
+      # rubocop:enable Lint/InterpolationCheck
     end
 
     def create_heroku_apps(flags)
@@ -206,7 +208,7 @@ def remove_config_comment_lines
         path = File.join(destination_root, "config/#{config_file}")
 
         accepted_content = File.readlines(path).reject { |line|
-          line =~ /^.*#.*$/ || line =~ /^$\n/
+          line =~ /^\s*#.*$/ || line =~ /^$\n/
         }
 
         File.open(path, "w") do |file|

spec/features/new_project_spec.rb

@@ -147,8 +147,10 @@
 
   it "sets action mailer default host and asset host" do
     config_key = "config.action_mailer.asset_host"
+    # rubocop:disable Lint/InterpolationCheck
     config_value =
-      %q{ENV\.fetch\("ASSET_HOST", ENV\.fetch\("APPLICATION_HOST"\)\)}
+      %q{"https://#{ENV\.fetch\("ASSET_HOST", ENV\.fetch\("APPLICATION_HOST"\)\)}}
+    # rubocop:enable Lint/InterpolationCheck
     expect(production_config).to match(/#{config_key} = #{config_value}/)
   end
 
@@ -214,7 +216,7 @@
     ]
 
     config_files.each do |file|
-      expect(file).not_to match(%r{.*#.*})
+      expect(file).not_to match(/^\s*#.*$/)
       expect(file).not_to eq(file.strip)
       expect(file).not_to match(%r{^$\n\n})
     end