fix: use an async event hook for custom_domain in AsyncManagementClient

src/auth0/management/management_client.py

@@ -42,6 +42,11 @@ def _enforce_custom_domain_whitelist(request: httpx.Request) -> None:
         del request.headers[CUSTOM_DOMAIN_HEADER]
 
 
+async def _enforce_custom_domain_whitelist_async(request: httpx.Request) -> None:
+    """httpx event hook for httpx.AsyncClient, which awaits its request hooks."""
+    _enforce_custom_domain_whitelist(request)
+
+
 def CustomDomainHeader(domain: str) -> RequestOptions:
     """Create request options that set the Auth0-Custom-Domain header for a single request.
 
@@ -522,7 +527,7 @@ def __init__(
             if httpx_client is None:
                 httpx_client = httpx.AsyncClient(timeout=timeout or 60, follow_redirects=True)
             httpx_client.event_hooks.setdefault("request", []).append(
-                _enforce_custom_domain_whitelist
+                _enforce_custom_domain_whitelist_async
             )
 
         # Encode client_info into Auth0-Client header to override default telemetry

tests/management/test_management_client.py

@@ -569,6 +569,46 @@ def test_non_whitelisted_paths_do_not_match(self, path):
         """Should not match non-whitelisted paths."""
         assert _is_path_whitelisted(path) is False
 
+    def test_sync_request_enforces_whitelist(self):
+        """Should send the header only on whitelisted paths for sync requests."""
+        sent = []
+
+        def handler(request):
+            sent.append(request)
+            return httpx.Response(200, json={})
+
+        client = ManagementClient(
+            domain="test.auth0.com",
+            token="my-token",
+            custom_domain="login.mycompany.com",
+            httpx_client=httpx.Client(transport=httpx.MockTransport(handler)),
+        )
+        client.users.get("auth0|abc123")
+        client.clients.get("abc123")
+
+        assert sent[0].headers[_CUSTOM_DOMAIN_HEADER] == "login.mycompany.com"
+        assert _CUSTOM_DOMAIN_HEADER not in sent[1].headers
+
+    async def test_async_request_enforces_whitelist(self):
+        """Should send the header only on whitelisted paths for async requests."""
+        sent = []
+
+        def handler(request):
+            sent.append(request)
+            return httpx.Response(200, json={})
+
+        client = AsyncManagementClient(
+            domain="test.auth0.com",
+            token="my-token",
+            custom_domain="login.mycompany.com",
+            httpx_client=httpx.AsyncClient(transport=httpx.MockTransport(handler)),
+        )
+        await client.users.get("auth0|abc123")
+        await client.clients.get("abc123")
+
+        assert sent[0].headers[_CUSTOM_DOMAIN_HEADER] == "login.mycompany.com"
+        assert _CUSTOM_DOMAIN_HEADER not in sent[1].headers
+
 
 class TestImports:
     """Tests for module imports."""