PageActionDescriptorChangeProvider does not invalidate the cache when a _PageStart outside of RazorPagesOption.BasePath is modified

[pranavkm]

The PageActionDescriptorProvider caches _PageStart factories and is invalidated when PageActionDescriptorChangeProvider is modifed.

/_PageStart.cshtml
/Pages                        <- BasePath
   /Index.cshtml

However, it specifically watches for cshtml files under the BasePath directory. This might miss changes to _PageStart items outside the BasePath.

[rynowak]

IMO that /_PageStart.cshtml should be totally ignored.

[rynowak]

I'm running into a related issue where a _PageStart in the same folder isn't even found.

services.AddMvc().AddRazorPagesOptions(options => options.RootDirectory = "/Pages");

Makes my /Pages/_PageStart.cshtml be totally ignored.

[rynowak]

@pranavkm - assigning to you to figure out. Please treat this as a dogfood blocker (and add a functional test).