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)