st collection = new tr.model.ObjectCollection({});
    const scopedId = new tr.model.ScopedId('ptr', '0x1000');
    collection.idWasCreated(
        scopedId, 'cat', 'Frame', 10);
    collection.addSnapshot(
        scopedId, 'cat', 'Frame', 10, {foo: 1});
    collection.autoDeleteObjects(15);

    const s10 = collection.getSnapshotAt(scopedId, 10);
    const i10 = s10.objectInstance;
    assert.strictEqual(15, i10.deletionTs);
  });

  test('differentScopes', function() {
    const collection = new tr.mode