Doesn't handle ASCII colors.

[JimBarrows]

The following should be colorized, and not showing the control codes to get the color:
[37mShowing off prove�[0m
� [32m✓ �[90mT is expected to be T�[0m
� [0m
�[32m✓ �[90m4 is expected to be 4�[0m
�[0m
�[32m✓ �[90m1 is not expected to be #\1�[0m
�[0m
�[32m✓ 1 test completed�[0m �[90m(0ms)�[0m

You can see what it's supposed to look like [https://github.com/fukamachi/prove](on the prove repo)