assertHTMLEqual doesn't account for all ASCII whitespace in a class attribute.

[Jon Dufresne]

From ​https://html.spec.whatwg.org/#classes

When specified on HTML elements, the class attribute must have a value that is a set of space-separated tokens representing the various classes that the element belongs to.

And "space-separated tokens" is defined as:

​https://html.spec.whatwg.org/#set-of-space-separated-tokens

A set of space-separated tokens is a string containing zero or more words (known as tokens) separated by one or more ASCII whitespace, where words consist of any string of one or more characters, none of which are ASCII whitespace.

And "ASCII whitespace" is defined as:

​https://infra.spec.whatwg.org/#ascii-whitespace

ASCII whitespace is U+0009 TAB, U+000A LF, U+000C FF, U+000D CR, or U+0020 SPACE.

The current implementation (copied and linked below) only accounts for a single space. Not all consecutive ASCII whitespace.

​https://github.com/django/django/blob/48235ba807483fe349d2dc66aaeddc0d03f8b0d4/django/test/html.py#L180-L187

        # Special case handling of 'class' attribute, so that comparisons of DOM
        # instances are not sensitive to ordering of classes.
        attrs = [
            (name, " ".join(sorted(value.split(" "))))
            if name == "class"
            else (name, value)
            for name, value in attrs
        ]

[Jon Dufresne]

​PR

[Carlton Gibson]

Yep. Great.

[Carlton Gibson <carlton.gibson@…>]

In b7a33ee4:

Fixed #30468 -- Fixed assertHTMLEqual() to handle all ASCII whitespace in a class attribute.