Resolving a relative URI Reference against a base with only an authority does not work

[aucampia]

From IETF RFC 3986 Uniform Resource Identifier (URI): Generic Syntax I would expect the following test to pass:

from rfc3986 import uri_reference  # type: ignore[import]
from rfc3986.uri import URIReference  # type: ignore[import]


def test_schema_only_base() -> None:
    relative_uri: URIReference = uri_reference("john.smith")
    base_uri: URIReference = uri_reference("example:")
    resolved_uri: URIReference = relative_uri.resolve_with(base_uri, strict=True)
    assert resolved_uri.unsplit() == "example:/john.smith"

This is because of:

5.2.1. Pre-parse the Base URI

Note that only the scheme component is required to be
present in a base URI; the other components may be empty or
undefined.

5.2.2. Transform References

# Branches that won't execute elided with [...]
if defined(R.scheme) then
   [...]
else
   if defined(R.authority) then
      [...]
   else
      if (R.path == "") then
         [...]
      else
         if (R.path starts-with "/") then
            [...]
         else
            T.path = merge(Base.path, R.path);
            T.path = remove_dot_segments(T.path);
         endif;
         T.query = R.query;
      endif;
      T.authority = Base.authority;
   endif;
   T.scheme = Base.scheme;
endif;

T.fragment = R.fragment;

5.2.3. Merge Paths

The pseudocode above refers to a "merge" routine for merging a
relative-path reference with the path of the base URI. This is
accomplished as follows:

• If the base URI has a defined authority component and an empty
  path, then return a string consisting of "/" concatenated with the
  reference's path; otherwise,

So according to this, my understanding is that, R, Base and T should be as follow:

R = URIReference(scheme=None, authority=None, path='john.smith', query=None, fragment=None)
Base = URIReference(scheme='example', authority=None, path=None, query=None, fragment=None)
T = URIReference(scheme='example', authority=None, path='/john.smith', query=None, fragment=None)

And T, when unsplit, will be "example:/john.smith". I may of course be missing something though, and if I am please do help me out here in seeing what it is.

When I run the actual test code it fails, so clearly the current implementation of RFC3986 in this library does not share my interpretation, it may be

$ pytest test_rfc3986.py -rA --log-level DEBUG
============================================================================ test session starts ============================================================================
platform linux -- Python 3.10.1, pytest-6.2.5, py-1.11.0, pluggy-1.0.0
rootdir: /home/iwana/sw/d/gitlab.com/aucampia/scraps
plugins: asyncio-0.16.0
collected 1 item                                                                                                                                                            

test_rfc3986.py F                                                                                                                                                     [100%]

================================================================================= FAILURES ==================================================================================
___________________________________________________________________________ test_schema_only_base ___________________________________________________________________________

    def test_schema_only_base() -> None:
        relative_uri: URIReference = uri_reference("john.smith")
        base_uri: URIReference = uri_reference("example:")
>       resolved_uri: URIReference = relative_uri.resolve_with(base_uri, strict=True)

test_rfc3986.py:8: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = URIReference(scheme=None, authority=None, path='john.smith', query=None, fragment=None)
base_uri = URIReference(scheme='example', authority=None, path=None, query=None, fragment=None), strict = True

    def resolve_with(self, base_uri, strict=False):
        """Use an absolute URI Reference to resolve this relative reference.
    
        Assuming this is a relative reference that you would like to resolve,
        use the provided base URI to resolve it.
    
        See http://tools.ietf.org/html/rfc3986#section-5 for more information.
    
        :param base_uri: Either a string or URIReference. It must be an
            absolute URI or it will raise an exception.
        :returns: A new URIReference which is the result of resolving this
            reference using ``base_uri``.
        :rtype: :class:`URIReference`
        :raises rfc3986.exceptions.ResolutionError:
            If the ``base_uri`` is not an absolute URI.
        """
        if not isinstance(base_uri, URIMixin):
            base_uri = type(self).from_string(base_uri)
    
        if not base_uri.is_absolute():
>           raise exc.ResolutionError(base_uri)
E           rfc3986.exceptions.ResolutionError: example: is not an absolute URI.

/home/iwana/.local/lib/python3.10/site-packages/rfc3986/_mixin.py:266: ResolutionError
========================================================================== short test summary info ==========================================================================
FAILED test_rfc3986.py::test_schema_only_base - rfc3986.exceptions.ResolutionError: example: is not an absolute URI.
============================================================================= 1 failed in 0.10s =============================================================================

[sigmavirus24]

This definitely seems like a bug. Well researched and reported! #82 should fix this up for you shortly

[sigmavirus24]

Released! 🎉