How to test for trailing whitespace?

In #62 I encountered a problem. I have a whitespace before comments (line comment 1, 2 and 3), but cannot write tests, because Rubocop complains during CI. Is this possible to:

* turn off Rubocop trailing whitespace check

or

* have snippet extractor cut trailing whitespace?

Start by reviewing issue #62, the repository’s RuboCop configuration, and the snippet-extractor test setup. Decide whether intentional trailing whitespace should be allowed in tests or removed during extraction; done means the comment examples can be tested without CI complaints.

Written by the indexing model from the issue text.