there are several flavors of base64 and in this kata padding is not required for either encoding or decoding. the description says :

Note: This kata uses the non-padding version ("=" is not added to the end).

Hi, the translator should have already fixed the problem now.
I'm marking the issue as resolved, tell me if there are any problems.

Incorrect expected output for randomised test in JS version of kata sometimes when we have 0 koef in input.

For example,

• Input
  xz-0bz
• Expected output
  -0bz+xz
• But should be
  xz

Like it was noticed before, tests in this kata doesn't properly check for padding.
It seems that there was a problem with = symbol in tests, but now it works fine with tests like these

Test.assertEquals('this is a string!'.toBase64(), 'dGhpcyBpcyBhIHN0cmluZyE=');
Test.assertEquals('dGhpcyBpcyBhIHN0cmluZyE='.fromBase64(), 'this is a string!');

This should be better added to test cases and maybe should be noticed in description, because at the moment there are many invalid solutions are present and Base64 which they generate and parse is actualy invalid too.