add tests for isNotificationScheduled

test/repositories/NotificationRepositorySharedTests.test.ts

@@ -181,5 +181,18 @@ describe.each(repositoryImplementations)('$name', (holder) => {
       };
       expect(mockCallback).toHaveBeenCalledWith(expectedEvent);
     });
-  })
+  });
+
+  describe("isNotificationScheduled", () => {
+    it("returns true if the notification is in the repo", async () => {
+      await repo.addOrUpdateNotification(notification);
+      const result = await repo.isNotificationScheduled(notification);
+      expect(result).toBe(true);
+    });
+
+    it("returns false if the notification isn't in the repo", async () => {
+      const result = await repo.isNotificationScheduled(notification);
+      expect(result).toBe(false);
+    })
+  });
 });