chore: add tests for unique index on email and org_id in users table

tests/integration/src/user/01_unique_index.py

@@ -0,0 +1,70 @@
+from http import HTTPStatus
+from typing import Callable
+
+import requests
+
+from fixtures.auth import USER_ADMIN_EMAIL, USER_ADMIN_PASSWORD
+from fixtures.types import Operation, SigNoz
+
+DUPLICATE_USER_EMAIL = "duplicate@integration.test"
+
+
+def test_duplicate_user_invite_rejected(
+    signoz: SigNoz,
+    create_user_admin: Operation,  # pylint: disable=unused-argument
+    get_token: Callable[[str, str], str],
+):
+    """
+    Verify that the unique index on (email, org_id) in the users table prevents
+    creating duplicate users. This invites a new user, accepts the invite, then
+    tries to invite and accept the same email again expecting a failure.
+    """
+    admin_token = get_token(USER_ADMIN_EMAIL, USER_ADMIN_PASSWORD)
+
+    # Step 1: Invite a new user.
+    invite_response = requests.post(
+        signoz.self.host_configs["8080"].get("/api/v1/invite"),
+        json={"email": DUPLICATE_USER_EMAIL, "role": "EDITOR"},
+        headers={"Authorization": f"Bearer {admin_token}"},
+        timeout=2,
+    )
+    assert invite_response.status_code == HTTPStatus.CREATED
+    first_invite_token = invite_response.json()["data"]["token"]
+
+    # Step 2: Accept the invite to create the user.
+    accept_response = requests.post(
+        signoz.self.host_configs["8080"].get("/api/v1/invite/accept"),
+        json={"token": first_invite_token, "password": "password123Z$"},
+        timeout=2,
+    )
+    assert accept_response.status_code == HTTPStatus.CREATED
+
+    # Step 3: Invite the same email again.
+    second_invite_response = requests.post(
+        signoz.self.host_configs["8080"].get("/api/v1/invite"),
+        json={"email": DUPLICATE_USER_EMAIL, "role": "VIEWER"},
+        headers={"Authorization": f"Bearer {admin_token}"},
+        timeout=2,
+    )
+
+    # The invite creation itself may be rejected if the app checks for existing users.
+    if second_invite_response.status_code != HTTPStatus.CREATED:
+        assert second_invite_response.status_code in (
+            HTTPStatus.CONFLICT,
+            HTTPStatus.BAD_REQUEST,
+        )
+        return
+
+    second_invite_token = second_invite_response.json()["data"]["token"]
+
+    # Step 4: Accept the second invite — should fail due to unique constraint.
+    second_accept_response = requests.post(
+        signoz.self.host_configs["8080"].get("/api/v1/invite/accept"),
+        json={"token": second_invite_token, "password": "password123Z$"},
+        timeout=2,
+    )
+    assert second_accept_response.status_code in (
+        HTTPStatus.CONFLICT,
+        HTTPStatus.BAD_REQUEST,
+        HTTPStatus.INTERNAL_SERVER_ERROR,
+    )