How could/should I state colon (punctuation) in a YAML file?

html ruby-on-rails ruby ruby-on-rails-3 yaml

You should be able to double quote the value:

test_key_html: "Test value:"

This avoids colon-confusion in the YAML and gets your colon into your HTML.

Consider this in irb:

>> { 'en' => { 'test_key_html' => 'Test value:' } }.to_yaml=> "--- \nen: \n  test_key_html: "Test value:"\n"

html ruby-on-rails ruby ruby-on-rails-3 yaml

Try

raw(t('test_key_html'))

Rails 3+ automattically escapes html markup

CodeHunter