Ding ding ding. Testcontainers is a fanatstic way to write the most important tests (arguably) for your app. Don't test E2E with a mock, just use a real database.
If that feels hard to you (to set up your app pointing to another DB, run a single E2E-testable part of your app with it's own DB connection, etc), fix that.
If that feels hard to you (to set up your app pointing to another DB, run a single E2E-testable part of your app with it's own DB connection, etc), fix that.