function testDeferrable_ExplicitTx_Delete_Error() {
  var parentRow = sampleRows[0];
  var childRow = sampleRows[1];

  var tx1 = db.createTransaction();
  var tx2 = null;
  return tx1.exec([
    db.insert().into(parentTable).values([parentRow]),
    db.insert().into(childTable).values([childRow])
  ]).then(function() {
    tx2 = db.createTransaction();
    return tx2.begin([parentTable, childTable]);
  }).then(function() {
    // Deleting parent even though the child row refers to it.
    return tx2.attach(db.delete().from(parentTable));
  }).then(function() {
    return lf.testing.util.assertPromiseReject(203, tx2.commit());
  });
}
Tests that a DEFERRABLE constraint violation during deletion, results in the
appropriate error when an explicit transaction is used.
@return {!IThenable}