':' is being considered a valid relative URI

[Silvanoc]

Describe the bug
The string ":" (simply a colon) is being considered a valid relative URI.
But, if I'm reading the specification right, it isn't a valid relative URI.

Expected result
uritools.isrelpath(":") returns False

Actual result
uritools.isrelpath(":") returns True

Reproduction steps

import uritools
print(uritools.isrelpath(":"))

[Silvanoc]

For example, this alternative Python URI validator also rejects ':' as a valid relative URI.

[Silvanoc]

This other alternative online validator is also rejecting it: https://0mg.github.io/tools/uri/

[tkem]

@Silvanoc: Thanks for your interest! Regarding ":" used as an URI, this is - for better or worse - interpreted as a simple path, and therefore as a valid relative URI:

>>> uritools.urisplit(":")
SplitResultString(scheme=None, authority=None, path=':', query=None, fragment=None)

According to RFC 3986, ":" belongs to

gen-delims  = ":" / "/" / "?" / "#" / "[" / "]" / "@"

and should therefore better be encoded if used in path components. However, uritools tries to follow the robustness principle of be strict in what you server, but be liberal in what you accept, and therefore a single ":" is accepted as a path.

[Silvanoc]

and should therefore better be encoded if used in path components

What I read in the RFC 3986 (end of the page) is "the conflicting data MUST be percent-encoded before the URI is formed" (formatting is mine). So I would say that : is not valid URIs according RFC 3986, since it doesn't delimit any data (and would therefore be part of the data).

uritools tries to follow the robustness principle of be strict in what you server, but be liberal in what you accept, and therefore a single ":" is accepted as a path.

IMHO having a strict flag or similar would be helpfull for this purpose. That way uritools could remain by default "liberal" on what it accepts, but get "strict" on demand.

Just to give you some context information. I'm not using uritools mostly due to this behaviour, which would force the project I'm collaborating on to make one of the tests less strict.
We have taken a different approach, so whatever feedback I provide you here is just part of my "sharing is caring" mindset.
I you don't want it, simply close this issue 🙂