HTTP Relative URL support in $ref

[wcloete]

Expected Behaviour

The OpenAPI 3.0 spec supports relative URLs in $ref definitions, but currently this ends up in a call to util.url.absurl which specifies that

Non-file URLs are left untouched.

So this results in a ResolutionError when using ResolvingParser on a server with its api in multiple files.

My question then is whether you would be open to a PR to add support for http(s) to util.url.absurl, or is this intentionally unsupported by design? (it seems like another 5-10 lines are needed) Or am I underestimating the problem?

Minimal Example Spec

To give you a working example I would have to expose my web server on the internet, but if you need more info I'll gladly provide.

Actual Behaviour

A ResolutionError is raised when using ResolvingParser on a server with its api in multiple files specified using relative URLs.

Steps to Reproduce

Environment

• OS: macOS Catalina
• Python version: 3.7
• Swagger/OpenAPI version used: 3.0.0
• Backend: N/A

[wcloete]

I think I've fixed this, (possibly only partly) in https://github.com/wcloete/prance.