diff --git a/tests/integration/_support/vertex.py b/tests/integration/_support/vertex.py
new file mode 100644
index 00000000000..af7178fa6e9
--- /dev/null
+++ b/tests/integration/_support/vertex.py
@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import json
+from typing import Final
+
+from cryptography.hazmat.primitives import serialization
+from cryptography.hazmat.primitives.asymmetric import rsa
+
+
+def service_account_json(project: str, token_url: str) -> str:
+    private_key: Final = (
+        rsa.generate_private_key(public_exponent=65537, key_size=2048)
+        .private_bytes(
+            serialization.Encoding.PEM,
+            serialization.PrivateFormat.PKCS8,
+            serialization.NoEncryption(),
+        )
+        .decode()
+    )
+    return json.dumps(
+        {
+            "type": "service_account",
+            "project_id": project,
+            "private_key_id": "scripted",
+            "private_key": private_key,
+            "client_email": f"scripted@{project}.iam.gserviceaccount.com",
+            "client_id": "0",
+            "auth_uri": f"{token_url}/_oauth/authorize",
+            "token_uri": f"{token_url}/_oauth/token",
+        }
+    )