848 hierarchical categories

[danieljsummers]

This implements the ability to have multiple category hierarchies attached to a single post (#848).

By default, everything works the way it currently does; a list of categories will be assembled for a single category hierarchy. The change implemented here is that, if a category is a list, setCategories() will switch into multiple category mode, and each top-level item in the list will be a category hierarchy itself.

categories:
- Example 1
- Example 2
- [Example 3, Subexample 3.1]

This will result in four different categories assigned to the post, with three different hierarchies (example-1, example-2, and example-3/subexample-3.1). The category generator already created index pages for intermediate categories, so [url]/category/example-3/ is a good URL, and would contain this post.

I have just forked/cloned the site repo, and will get the documentation for this change there. Additionally, I plan to look at the WordPress export format; if it exports the categories in their hierarchy, I'll see if I can PR a change to that migrator to bring the hierarchies over intact.

• Add test cases for the changes.
• Passed the CI test.

[coveralls]

Coverage increased (+0.006%) to 97.164% when pulling 3f45e26 on danieljsummers:848-hierarchical-categories into dfb5a4b on hexojs:master.

[danieljsummers]

No fat arrow functions, huh? :) I'll have that pushed up momentarily.

[coveralls]

Coverage increased (+0.006%) to 97.164% when pulling a57f3c1 on danieljsummers:848-hierarchical-categories into dfb5a4b on hexojs:master.

[NoahDragon]

Add reference #848

[danieljsummers]

I realized that I didn't check for duplicate parents not being added. I wrote a test to check for that, and it passed with no code changes. I'll commit the test to this branch.

[coveralls]

Coverage increased (+0.006%) to 97.164% when pulling ce337a3 on danieljsummers:848-hierarchical-categories into dfb5a4b on hexojs:master.

[danieljsummers]

FWIW, the code here enabled me to move my tech blog, which is live here!

[NoahDragon]

LGTM

[NoahDragon]

@danieljsummers The live sample is really cool. This is also a major feature will in 4.0. #2492

Thanks for the contribution!

[NoahDragon]

Add reference: need to update hexo site when the feature released. hexojs/site#550