factory_girl

https://github.com/thoughtbot/factory_girl

Ruby

A library for setting up Ruby objects as test data.

Mail::Message#add_date

Creates a new empty Date field and inserts it in the correct order
into the Header.  The DateField object will automatically generate
DateTime.now's date if you try and encode it or output it to_s without
specifying a date yourself.

It will preserve any date you specify if you do.

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-add_date-for-pr

# Commit to git

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

# 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-add_date-for-pr

hub pull-request

# Celebrate!