add trusted pseudo-classes argument

[tbicr]

It useful to wide cssselect pseudo-classes support like :not(), :nth-child(), :nth-last-child, :nth-of-type(), :nth-last-of-type() and etc. For this case pseudo-classes as :hover, :active and etc. will processed but not left in style attribute, so you must use for this keep_style_tags argument.

[peterbe]

I don't like the word "trusted". If that's the parameter name I'd expect the value to be a list of pseudo classes. Like:

    trusted_pseudoclasses=[':foo', ':bar']

...or something.

Perhaps you mean to call it trust_pseudoclasses=False which would make it a verb.

[peterbe]

Note how the parameter in that same signature is exclude_pseudoclasses. "verb_noun"

[peterbe]

Why would it be False by default?
Looking at your added unit test, it looks like a really useful feature that isn't controversial.
The reason exclude_pseudoclasses is True by default is because you can't keep pseudo classes in style attributes so keeping them is kinda silly.

[peterbe]

Your code has diverged from master. Can you rebase up your code and push back into the pull request?

[tbicr]

I rebase code, fix test_selector to is_valid_selector (thanks), trusted_pseudoclasses to trust_pseudoclasses (sorry english is not my first language), but now this pull request tests broken, because sheet = cssutils.parseString(css_body) do not support test selectors. So with current cssutils no reason merge this patch.

trust_pseudoclasses is False by default to no change previous behaviour.

[peterbe]

Great work! I'm currently a bit swamped as tomorrow is the start of the new quarter but I've starred this on my todo list and I'll try to see what I can do to make it work again.

[peterbe]

What version of lxml added SelectorError?
Once we know that setup.py needs to be modified and look something like lxml>=x.y.z

[tbicr]

SelectorError available in lxml=>3.0 version.

[peterbe]

Test fail quite hard.
See https://gist.github.com/peterbe/9927429

Would you mind looking at that first?

[tbicr]

As I said before issue in code sheet = cssutils.parseString(css_body), because it not recognize test selector: div:not(:nth-child(1)) which normal for lxml. So issue more in cssutils then premailer, but my patch was broken after adding cssutils.

I created issue for cssutils: https://bitbucket.org/cthedot/cssutils/issue/43/two-nested-pseudo-classes-with-brackets.
I can change on test_trusted_pseudo current to more easy selector div:not(:first) which will be pass, but div:not(:nth-child(1)) still will be skipped untill it will not be fixed on cssutils.

PS. I fixed test_trusted_pseudo_bad_selector because div:not(:not(:first-child)) already bad selector and filtered with cssselect, so look like SelectorError checking is duplicate of cssselect filtering bad selectors logic.

[peterbe]

Any chance we can revive this?