Mock Modal module at import time in test conftest

Patch modal decorators to be pass-through functions so
github_webhook handler can be tested without Modal runtime.

Author: manascb1344

tests/conftest.py

@@ -1,6 +1,30 @@
+import sys
+from unittest.mock import MagicMock
+
 import pytest
 
 
+@pytest.fixture(autouse=True, scope="session")
+def _mock_modal_decorators():
+    mock_modal = MagicMock()
+    mock_modal.Image.from_registry.return_value = MagicMock()
+    mock_modal.App.return_value = MagicMock()
+    mock_modal.Secret.from_name.return_value = MagicMock()
+    mock_modal.Queue.from_name.return_value = MagicMock()
+    mock_modal.Sandbox.list.return_value = []
+    mock_modal.fastapi_endpoint = lambda **kwargs: lambda f: f
+    mock_app = MagicMock()
+    mock_app.function = lambda **kwargs: lambda f: f
+    mock_app.app_id = "test-app-id"
+    mock_modal.App.return_value = mock_app
+
+    sys.modules["modal"] = mock_modal
+
+    yield
+
+    sys.modules.pop("modal", None)
+
+
 @pytest.fixture(autouse=True)
 def set_env(monkeypatch):
     monkeypatch.setenv("WEBHOOK_SECRET", "test-secret")