factory_girl

https://github.com/thoughtbot/factory_girl

Ruby

A library for setting up Ruby objects as test data.

Mail::Message#html_part=

Helper to add a html part to a multipart/alternative email.  If this and
text_part are both defined in a message, then it will be a multipart/alternative
message and set itself that way.

Source | Google | Stack overflow

Edit

git clone [email protected]:thoughtbot/factory_girl.git
cd factory_girl
open

Contribute

# Make a new branch

git checkout -b -your-name--update-docs-Mail--Message-html_part--for-pr

# Commit to git

git add git commit -m "better docs for Mail::Message#html_part="

# Open pull request

gem install hub # on a mac you can `brew install hub`

hub fork

git push <your name> -your-name--update-docs-Mail--Message-html_part--for-pr

hub pull-request

# Celebrate!