Add suffix to doc context. Fixes #1873.

[ericholscher]

Not sure the best way to get the suffix from the docname, but this seems to work well. Happy to clean this up if there's a better way to do it.

Refs #1873

[ericholscher]

Any thoughts?

[RobRuana]

This could use at least one test to verify it is working correctly.

Also, are we sure that there will always be a suffix? If not you'd end up with the whole path in suffix. Maybe something like:

docpath = self.env.doc2path(docname)
suffix = ""
if "." in docpath:
    suffix = docpath.split('.')[-1]

[shimizukawa]

LGTM.

self.env.doc2path(docname) always return a path with suffix.
If worry about it, we can use os.path.splitext(self.env.doc2path(docname))[-1] more safely.

[ericholscher]

Yea, is there a specific test that I should be adding this to? I looked through, but didn't find a great place to put it, but it's likely I missed it.

[shimizukawa]

If I write a test, it will be written to tests/test_build_html.py.
However, there is no existing tests to check the context.
You can either newly prepared, or not write the test :/

[ericholscher]

Yea, that sounds like a good amount of work. If there was something that was already introspecting the inner build state, I would happily add another, but I don't have time currently to build a full test around it.

[shimizukawa]

OK, I'm going to merge this.
Before that, @ericholscher please can you squash the commits into 1 commit?

[ericholscher]

Squashed commits.

[shimizukawa]

Merged. Thanks!