Make BlockContentType use a route provider instead of hard-coded routes

Thanks for getting the ball rolling on this effort again! Adding parent issue.

I'm expecting this patch might fail a Breadcrumb test the way #2919891: Make Vocabulary use a route provider instead of hard-coded routes did when "Edit " was added to the breadcrumb, hopefully that's the only one.

As I suspected. This should fix it.

Something that makes me hesitate on issues like this is that it's getting harder and harder to figure out where a page is coming from. Previously I could grep for the path in routing files, find the route, and then grep for its callback or default or whatever.

The dynamic route generation is probably still much better DX because there's less boilerplate, but do we have a strategy for documenting this or helping people figure out what code in their codebase is providing the page they're looking at? There doesn't seem to be anything about route providers on the routing API documentation page which was probably missed docs gate for the issue that added Drupal\Core\Entity\Routing\AdminHtmlRouteProvider. That was #2578955: Implement auto route generation but DON'T use it for all core entities, just before release, and it looks like it updated the entity section of the handbook rather than the routing section.

Leaving RTBC because this concern isn't in this issue's scope, but maybe we should file a followup that adds a brief paragraph to the routing page linking the entity page?

Are the routes still the same with the new route provider?

Yes, they're defined in the annotations.

* links = {
* "delete-form" = "/admin/structure/block/block-content/manage/{block_content_type}/delete",
* "edit-form" = "/admin/structure/block/block-content/manage/{block_content_type}",
* "collection" = "/admin/structure/block/block-content/types",
* },

I have also eyeballed them and they're definitely the same.

Odd how add-form isn't there though, and edit-form wasn't in the yaml file either.

I agree with you re documentation - I wouldn't have known where to start looking on this without a pointer from @larowlan

Opened #2939755: Expand routing.api.php to include route subscribers and entity route providers for the followup.

Re #9: Yes, the routes are the same but for minor changes in the title which we have decided in related issues that are actually positive as they lead to more consistency across the entity types.

Will send for a re-test as I don't think the test failure is related.