Mock out app NotificationSender during testing

tests/conftest.py

@@ -12,7 +12,7 @@ from atst.database import db as _db
 from atst.queue import queue as atst_queue
 import tests.factories as factories
 from tests.mocks import PDF_FILENAME, PDF_FILENAME2
-from tests.utils import FakeLogger
+from tests.utils import FakeLogger, FakeNotificationSender
 
 from datetime import datetime, timedelta
 from cryptography.hazmat.primitives.asymmetric import rsa
@@ -307,3 +307,13 @@ def mock_logger(app):
     yield app.logger
 
     app.logger = real_logger
+
+
+@pytest.fixture
+def mock_notification_sender(app):
+    real_notification_sender = app.notification_sender
+    app.notification_sender = FakeNotificationSender()
+
+    yield app.notification_sender
+
+    app.notification_sender = real_notification_sender

tests/utils.py

@@ -1,5 +1,8 @@
 from flask import template_rendered
 from contextlib import contextmanager
+from unittest.mock import Mock
+
+from atst.utils.notification_sender import NotificationSender
 
 
 @contextmanager
@@ -37,3 +40,6 @@ class FakeLogger:
         self.messages.append(msg)
         if "extra" in kwargs:
             self.extras.append(kwargs["extra"])
+
+
+FakeNotificationSender = Mock(spec=NotificationSender)