undefined method `assert_no_difference’ and `assert_difference’

I’ve been upgrading some old code and noticed that my unit tests started spitting out a lot of errors like this:

undefined method `assert_no_difference'
</pre>

and


undefined method `assert_difference'
</pre>

It turns out that I needed to change my base classes from Test::Unit::TestCase to ActiveSupport::TestCase:


class UserTest < Test::Unit::TestCase
  # stuff
end
</pre>

changes to:


class UserTest < ActiveSupport::TestCase
  # stuff
end
</pre>