bash-3.00$ ruby test_bytes.rb 
Loaded suite test_bytes
Started

Finished in 0.003285 seconds.

0 tests, 0 assertions, 0 failures, 0 errors
bash-3.00$ 

So I put 

class TestBytes < Test::Unit::TestCase

in the appropriate place (after the include) and ran the test, and two failed:

bash-3.00$ ruby test_bytes.rb 
Loaded suite test_bytes
Started
FF
Finished in 0.02716 seconds.

  1) Failure:
test_bits(TestBytes) [test_bytes.rb:15]:
<"011010101010"> expected but was
<"11010101010">.

  2) Failure:
test_bytes(TestBytes) [test_bytes.rb:40]:
<2938338195> expected but was
<2474320815>.

2 tests, 8 assertions, 2 failures, 0 errors
bash-3.00$