Add xtask support for refresh slide list.

[egithinji]

Adds support for a refresh-slide-list argument when running the command cargo xtask web-tests. Allows one to also specify an optional book html directory if one uses the refresh-slide-list argument. Fixes #2744 .

[michael-kerscher]

I'm sorry for the huge delay. I already prepared my review but somehow did not click the submit button...

[egithinji]

Hi @michael-kerscher . I noticed a difference in behavior when passing a directory using the full path (e.g. cargo xtask web-tests -d /usr/.../comprehensive-rust/book/html) vs from relative the workspace directory (e.g. cargo xtask web-tests -d book/html).

When using the full path, the slide list gets recreated but it seems like the actual testing of the slide dimensions doesn't happen. When using the shorter path from the workspace directory, it seems to work as expected. Is there a difference in how these paths are treated from within the web tests?

[michael-kerscher]

Hmm, if that is an issue for the actual test runner, this would be some interaction with npm or something inside wdio. I need to look at this

[michael-kerscher]

Absolute paths are fine, relative paths have conflicting usage, once with the CARGO_WORKSPACE_DIR/ and once with CARGO_WORKSPACE_DIR/tests/ (due to different working directories being used). You can resolve this issue by just converting the relative path to an absolute path. This also checks the directory and can provide early errors if the directory is wrong or does not exist

[michael-kerscher]

looks good to me now!