DirectiveDescriptorBuild should throw for directives that wouldn't be parsed correctly

[pranavkm]

For instance DirectiveDescriptorBuilder.Create("my-directive").Build() works correctly, but the parser requires an identifier token to be a descriptor name.

[rynowak]

Wouldn't this parse as @my-directive? This seems totally legal and reasonable to me.

[NTaylorMullen]

It could, but that's not what we've allowed in Razor in the past. We should enforce a convention. Up till today we've followed the camel case convention for Razor directives, i.e. @addTagHelper not @add-tag-helper

[pranavkm]

I think it parsed it as two separate tokens when I tried this in a test. We should either support it in the parser or throw ahead of time. I assumed we were 🐫 casers, hence the work item.

[pranavkm]

tl,dr: 🐫 > 🐍

[rynowak]

Ah I see. We should define the set of characters that are allowed in directives and validate that. Conventions are just conventions, not rules.