I'll mark this as resolved.

Is this issue resolved?

Thanks. I think I've fixed that bug now. It was just the message generating that wasn't right. Still unsure what causes messages to be clipped; maybe there's an upward limit for test failure messages...

Just want to point out: [undefined] or [undefined, undefined] is not the same as undefined. If there are no valid values, undefined should be returned. If there is one valid value, [value] should be returned. If there are two valid values, [value1, value2] should be returned.

Could you give me direct copy-paste examples of the errors referred to? I'm talking about ones which say something like expected: x = undefined.

1. There are randomly-generated tests after the basic ones; that is probably why your code fails at different points every time. It should stop everything if one of the tests fails, however. Are you sure there is more than one failed test?
2. As for the error messages getting cut off, I have seen this before, but not been able to figure out what causes the bug. Sorry about that. Oh, and if you see any messages with expected: x = undefined, that would be a bug in my testing code, though I can't figure out what could be causing it. If you do see that in the logs, please let me know what the quadratic equation was so I can try and fix the bug.