Make Registry.contents raise NoSuchResource when needed.

Previously it was propagating the KeyError (which we already don't do
elsewhere on other registry methods).

docs/changes.rst

@@ -2,6 +2,11 @@
 Changelog
 =========
 
+v0.35.0
+-------
+
+* Ensure that ``Registry.contents()`` also raises ``NoSuchResource`` exceptions for nonexistent resources, not ``KeyError`` (which is an implementation detail).
+
 v0.34.0
 -------
 

referencing/_core.py

@@ -477,9 +477,7 @@ def contents(self, uri: URI) -> D:
         """
         Retrieve the (already crawled) contents identified by the given URI.
         """
-        # Empty fragment URIs are equivalent to URIs without the fragment.
-        # TODO: Is this true for non JSON Schema resources? Probably not.
-        return self._resources[uri.rstrip("#")].contents
+        return self[uri].contents
 
     def crawl(self) -> Registry[D]:
         """

referencing/tests/test_core.py

@@ -188,6 +188,12 @@ def test_contents_strips_empty_fragments(self):
             == {"ID": uri + "#"}
         )
 
+    def test_contents_nonexistent_resource(self):
+        registry = Registry()
+        with pytest.raises(exceptions.NoSuchResource) as e:
+            registry.contents("urn:example")
+        assert e.value == exceptions.NoSuchResource(ref="urn:example")
+
     def test_crawled_anchor(self):
         resource = ID_AND_CHILDREN.create_resource({"anchors": {"foo": "bar"}})
         registry = Registry().with_resource("urn:example", resource)