Well yeah, sometimes messages from JUnit can be confusing :( The special characters you see are not a part of the string. That's how JUnit attempts to hint you where your answer differs from the expected one. Expected and actual values are different somewhere in between the brackets.

If it was indeed in Java, there are no other characters. If it wasn't, raise another issue, stating which one it was.

When reporting an issue, state the language you're referring to, this kata has many, is it Java?