@Test
public void testOp0() {

    // Check that OP_0 doesn't NPE and pushes an empty stack frame.
    Transaction tx = new Transaction(PARAMS);
    tx.addInput(new TransactionInput(PARAMS, tx, new byte[] {}));
    Script script = new ScriptBuilder().smallNum(0).build();
    LinkedList<byte[]> stack = new LinkedList<byte[]>();
    Script.executeScript(tx, 0, script, stack, Script.ALL_VERIFY_FLAGS);
    assertEquals("OP_0 push length", 0, stack.get(0).length);
}