Comment 4 for bug 672056

Okay, I see that doctest bug, it's filed upstream as <http://bugs.python.org/issue1293741> and is actually fixed in Python 2.7 despite the grousing there.

However I don't the same behaviour with that kind of test using testtools, as the exception is trapped when formatting the output and displayed unhelpfully, but safely, as:

    Traceback (most recent call last):
      File "C:\Python24\lib\doctest.py", line 2157, in runTest
        raise self.failureException(self.format_failure(new.getvalue()))
    AssertionError: <unprintable AssertionError object>

So, what version of testtools are you running there?