Set action_mailer.default_url_options values in development and test

[stevepolitodesign]

Motivation / Background

Prior to this commit, new Rails applications would raise ActionView::Template::Error if a mailer included a url built with a *_path helper.

Since we already know new apps will be served on localhost:3000, we set this as the value in development.

In an effort to remain consistent with existing patters, we set the host to www.example.com in test.

Additional information

If we feel this is not the right solution, how do we feel about at least adding these values, but commented out?

Checklist

Before submitting the PR make sure the following are checked:

• This Pull Request is related to one change. Changes that are unrelated should be opened in separate PRs.
• Commit message has a detailed description of what changed and why. If this PR fixes a related issue include it in the commit message. Ex: [Fix #issue-number]
• Tests are added or updated if you fix a bug or add a feature.
• CHANGELOG files are updated for the changed libraries if there is a behavior change or additional feature. Minor bug fixes and documentation changes should not be included.

[stevepolitodesign]

Even though we can set this to anything, I felt it was important to keep it consistent with what Rails is served on, in an effort to make previews link to the application.

[timwis]

This sounds like a helpful change—thanks! Quick question: The bin/rails server command allows a --port XXXX flag (and with bin/dev you set it via an env var, e.g. PORT=XXXX bin/dev). Any reason not to use that value, with a default of 3000? I ask because I often use that flag when I have multiple rails apps running.

[stevepolitodesign]

That's a great observation. I think we'd somehow need access to the value set in Rails::Commands::Server::ServerCommand:

rails/railties/lib/rails/commands/server/server_command.rb

Lines 213 to 215 in bf8e0f5

	def port
	options[:port] || ENV.fetch("PORT", DEFAULT_PORT).to_i
	end

I attempted the following implementation, but if ENV["PORT"] is not set, it won't match what's passed to the --port flag.

config.action_mailer.default_url_options = { host: "localhost", port: ENV.fetch("PORT", 3000).to_i }

However, this seemed to work for the following cases:

1. When ENV["PORT"] is supplied
2. When --port is supplied.
3. When neither ENV["PORT"] nor --port is supplied (defaulting to 3000)

config.action_mailer.default_url_options = { host: "localhost", port: Rails::Server::Options.new.parse!(ARGV)[:Port] }