Also suggest a correct pointer for #/.

Refs: python-jsonschema/jsonschema#1070

Author: Julian

docs/changes.rst

@@ -2,6 +2,11 @@
 Changelog
 =========
 
+v0.26.2
+-------
+
+* Also suggest a proper JSON Pointer for users who accidentally use ``#/`` and intend to refer to the entire resource.
+
 v0.26.1
 -------
 

referencing/exceptions.py

@@ -91,7 +91,14 @@ class PointerToNowhere(Unresolvable):
     resource: Resource[Any]
 
     def __str__(self):
-        return f"{self.ref!r} does not exist within {self.resource.contents!r}"
+        msg = f"{self.ref!r} does not exist within {self.resource.contents!r}"
+        if self.ref == "/":
+            msg += (
+                ". The pointer '/' is a valid JSON Pointer but it points to "
+                "an empty string property ''. If you intended to point "
+                "to the entire resource, you should use '#'."
+            )
+        return msg
 
 
 @frozen

referencing/tests/test_core.py

@@ -723,6 +723,23 @@ def test_lookup_non_existent_pointer_to_array_index(self):
             resource=resource,
         )
 
+    def test_lookup_pointer_to_empty_string(self):
+        resolver = Registry().resolver_with_root(Resource.opaque({"": {}}))
+        assert resolver.lookup("#/").contents == {}
+
+    def test_lookup_non_existent_pointer_to_empty_string(self):
+        resource = Resource.opaque({"foo": {}})
+        resolver = Registry().resolver_with_root(resource)
+        with pytest.raises(
+            exceptions.Unresolvable,
+            match="^'/' does not exist within {'foo': {}}.*'#'",
+        ) as e:
+            resolver.lookup("#/")
+        assert e.value == exceptions.PointerToNowhere(
+            ref="/",
+            resource=resource,
+        )
+
     def test_lookup_non_existent_anchor(self):
         root = ID_AND_CHILDREN.create_resource({"anchors": {}})
         resolver = Registry().with_resource("urn:example", root).resolver()