List late registered protocols (fsspec#358)

* tests: check if late registered fsspec impls are listed

* upath.registry.available_implementations: add protocols from fsspec registry

Author: ap--

upath/registry.py

@@ -44,6 +44,7 @@
 
 from fsspec.core import get_filesystem_class
 from fsspec.registry import known_implementations as _fsspec_known_implementations
+from fsspec.registry import registry as _fsspec_registry
 
 import upath
 
@@ -148,11 +149,10 @@ def available_implementations(*, fallback: bool = False) -> list[str]:
         If True, also return protocols for fsspec filesystems without
         an implementation in universal_pathlib.
     """
-    impl = list(_registry)
     if not fallback:
-        return impl
+        return list(_registry)
     else:
-        return list({*impl, *list(_fsspec_known_implementations)})
+        return list({*_registry, *_fsspec_registry, *_fsspec_known_implementations})
 
 
 def register_implementation(

upath/tests/test_registry.py

@@ -1,5 +1,12 @@
+import random
+import string
+
 import pytest
-from fsspec.registry import known_implementations
+from fsspec.implementations.local import LocalFileSystem
+from fsspec.registry import _registry as fsspec_registry_private
+from fsspec.registry import known_implementations as fsspec_known_implementations
+from fsspec.registry import register_implementation as fsspec_register_implementation
+from fsspec.registry import registry as fsspec_registry
 
 from upath import UPath
 from upath.registry import available_implementations
@@ -69,9 +76,29 @@ def test_available_implementations():
     assert set(impl) == IMPLEMENTATIONS
 
 
-def test_available_implementations_with_fallback():
+@pytest.fixture
+def fake_registered_proto():
+    fake_proto = "".join(random.choices(string.ascii_lowercase, k=8))
+
+    class FakeRandomFS(LocalFileSystem):
+        protocol = fake_proto
+
+    fsspec_register_implementation(fake_proto, FakeRandomFS)
+    try:
+        yield fake_proto
+    finally:
+        fsspec_registry_private.pop(fake_proto, None)
+
+
+def test_available_implementations_with_fallback(fake_registered_proto):
     impl = available_implementations(fallback=True)
-    assert set(impl) == IMPLEMENTATIONS.union(list(known_implementations))
+    assert fake_registered_proto in impl
+    assert set(impl) == IMPLEMENTATIONS.union(
+        {
+            *fsspec_known_implementations,
+            *fsspec_registry,
+        }
+    )
 
 
 def test_available_implementations_with_entrypoint(fake_entrypoint):