class ActiveSupport::TestCase

* +:alpha+ (equivalent to +:sorted+)
* +:sorted+ (to run tests alphabetically by method name)
* +:parallel+ (to run tests in parallel)
* +:random+ (to run tests in random order)
Valid values are:

ActiveSupport::TestCase.test_order = :random # => :random

Sets the order in which test cases are run.

def test_order=(new_order)
  ActiveSupport.test_order = new_order
end