Typo in CS1632_Lecture6_UnitTesting.pdf

[bvalley]

On the slide for "Minitest Assertions", instead of assert_equals it should be assert_equal for Ruby.

-brv11

[jordangrogan]

Likewise, on slide 19, refute_equals should be refute_equal.
Also, on slide 18, assert_true should just be assert, and on slide 19, refute_true should just be refute.