Function run_test_app 

pub fn run_test_app<AppShape, WorkerShape, Test>(
    modules: &[Module],
    app: impl AppWiring<AppShape>,
    worker: impl WorkerWiring<WorkerShape>,
    test: impl FnOnce(TestApp) -> Test,
)
where
    Test: Future<Output = ()>,

The runtime is shut down before the database is dropped, so no app connection holds the drop up.