Fix CloudPath.__truediv__ to return NotImplemented (#480)

Co-authored-by: Jay Qi <[email protected]>

Author: jayqi

HISTORY.md

@@ -1,5 +1,9 @@
 # cloudpathlib Changelog
 
+## Unreleased
+
+- Fixed `CloudPath(...) / other` to correctly attempt to fall back on `other`'s `__rtruediv__` implementation, in order to support classes that explicitly support the `/` with a `CloudPath` instance. Previously, this would always raise a `TypeError` if `other` were not a `str` or `PurePosixPath`. (PR [#479](https://github.com/drivendataorg/cloudpathlib/pull/479))
+
 ## v0.20.0 (2024-10-18)
 
 - Added support for custom schemes in CloudPath and Client subclases. (Issue [#466](https://github.com/drivendataorg/cloudpathlib/issues/466), PR [#467](https://github.com/drivendataorg/cloudpathlib/pull/467))

cloudpathlib/cloudpath.py

@@ -888,7 +888,7 @@ def _dispatch_to_path(self, func: str, *args, **kwargs) -> Any:
 
     def __truediv__(self, other: Union[str, PurePosixPath]) -> Self:
         if not isinstance(other, (str, PurePosixPath)):
-            raise TypeError(f"Can only join path {repr(self)} with strings or posix paths.")
+            return NotImplemented
 
         return self._dispatch_to_path("__truediv__", other)
 

tests/test_cloudpath_manipulation.py

@@ -204,3 +204,28 @@ def test_parser(rig):
     else:
         # always posixpath since our dispath goes to PurePosixPath
         assert rig.create_cloud_path("a/b/c").parser == posixpath
+
+
+def test_truediv_fallback(rig):
+    """Another class with __rtruediv__ method should be able to use / operator with CloudPath."""
+
+    class CustomClassSupportsCloudPath:
+        def __init__(self, value: str):
+            self.value = value
+
+        def __rtruediv__(self, other):
+            if isinstance(other, CloudPath):
+                return other / self.value
+            return NotImplemented
+
+    assert rig.create_cloud_path("a/b") / CustomClassSupportsCloudPath(
+        "c"
+    ) == rig.create_cloud_path("a/b/c")
+
+    # Expect TypeError if / operation with CloudPath is not supported
+    class CustomClassDoesNotSupportCloudPath:
+        def __init__(self, value: str):
+            self.value = value
+
+    with pytest.raises(TypeError):
+        rig.create_cloud_path("a/b") / CustomClassDoesNotSupportCloudPath("c")