monitor.provide_secret(281474976710655, secret.clone(), None).unwrap();
assert_eq!(monitor.payment_preimages.len(), 15);
test_preimages_exist!(&preimages[0..10], monitor);
test_preimages_exist!(&preimages[15..20], monitor);
// Now provide a further secret, pruning preimages 15-17
monitor.provide_secret(281474976710655, secret.clone(), None).unwrap();
assert_eq!(monitor.payment_preimages.len(), 15);
test_preimages_exist!(&preimages[0..10], monitor);
test_preimages_exist!(&preimages[15..20], monitor);
// Now provide a further secret, pruning preimages 15-17