How does one actually use miniunit, if the normal test/unit is present?

For example, when I try to run miniunit's own tests:

$ ruby test_test_case.rb
test_test_case.rb:8: uninitialized constant MiniTest (NameError)

Or is miniunit only intended for use in a minimal environment where 
test/unit is not present?

This is mostly idle curiosity. I'm playing with some extensions to the 
test/unit framework, and will probably start with miniunit instead. For 
this purpose, I can just copy and rename, so that miniunit isn't 
shadowed by test/unit.

-- 
       vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407