It's already in the example in the description, too late to change it too.

Test data strings currently include a space before punctuation. This is not conventional and should be corrected. Most people starting this challenge will try to solve for "Conventional sentence strings like this!" and not "Wacky strings that end like this !" Please remove unnecessary spaces before punctuation in the test data, or change the description to hint at this 'gotcha'. Thanks in advance.

Thanks for taking the time to write that out, Krakonosh!