Issue with whitespace_after_* not fixable

[AryazE]

I have to transform (using a libcst.CSTTransformer) some 3rd party code, which might contain statements like assert("foo") == "foo".
Although this is a valid python code, I get the error libcst._nodes.base.CSTValidationError: Must have at least one space after 'assert'.
I cannot fix this in the leave_Assert hook, as it is called after validation, and I cannot fix it in the visit_Assert hook, as the object node is frozen.
Currently, the only option I can think of is to do a regex search and replace before LibCST to add the missing whitespace and then feed it to my transformer.
Is there any easier way to do this, preferably within LibCST?

[kiri11]

Seems like duplicate of #1095
UPDATE: Okay, maybe it's not the same, just similar. Here is assert, and there is while.
UPDATE2: I was wrong, this is not an issue with the validator, I was just trying to add a node without parentheses.

[kiri11]

@AryazE I had a similar issue. However, the LibCST validator is working correctly here by preventing me from generating incorrect code.

I fixed my code and might help you if you share what are you trying to do. I guess you did the same mistake by adding a new node without parentheses. LibCST does not automatically add whitespace or parentheses for you.

Here is what I did: just copied the parentheses from the node I was trying to replace:

return new_node.with_changes(
    lpar=updated_node.lpar,
    rpar=updated_node.rpar
)