Improve api_url detail usage

gcapi/apibase.py

@@ -146,9 +146,10 @@ def iterate_all(self, params=None) -> Iterator[T]:
     def detail(
         self, pk=None, api_url=None, **params
     ) -> Generator[T, dict[Any, Any], T]:
-        if all((pk, params)):
-            raise ValueError("Only one of pk or params must be specified")
-
+        if sum(bool(arg) for arg in [pk, api_url, params]) != 1:
+            raise ValueError(
+                "Exactly one of pk, api_url, or params must be specified"
+            )
         if pk is not None or api_url is not None:
             if pk is not None:
                 request_kwargs = dict(path=urljoin(self.base_path, pk + "/"))

tests/integration_tests.py

@@ -368,7 +368,7 @@ def test_get_reader_study_by_slug(local_grand_challenge):
     assert by_pk == by_slug == by_api_url
 
 
-@pytest.mark.parametrize("key", ["slug", "pk"])
+@pytest.mark.parametrize("key", ["slug", "pk", "api_url"])
 def test_detail_no_objects(local_grand_challenge, key):
     c = Client(
         base_url=local_grand_challenge, verify=False, token=READERSTUDY_TOKEN
@@ -378,6 +378,24 @@ def test_detail_no_objects(local_grand_challenge, key):
         c.reader_studies.detail(**{key: "foo"})
 
 
+@pytest.mark.parametrize(
+    "keys",
+    (
+        ("api_url", "pk", "slug"),
+        ("api_url", "pk"),
+        ("api_url", "slug"),
+        ("pk", "slug"),
+    ),
+)
+def test_detail_multiple_args(local_grand_challenge, keys):
+    c = Client(
+        base_url=local_grand_challenge, verify=False, token=READERSTUDY_TOKEN
+    )
+
+    with pytest.raises(ValueError):
+        c.reader_studies.detail(**{k: "foo" for k in keys})
+
+
 def test_detail_multiple_objects(local_grand_challenge):
     c = Client(token=ADMIN_TOKEN, base_url=local_grand_challenge, verify=False)