pytest: test withdrawal transactions' nLockTime

tests/test_wallet.py

@@ -698,3 +698,44 @@ def test_fundchannel_listtransaction(node_factory, bitcoind):
 
     tx = [t for t in txs if t['hash'] == txid][0]
     assert tx['blockheight'] == 0
+
+
+def test_withdraw_nlocktime(node_factory):
+    """
+    Test that we don't set the nLockTime to 0 for withdrawal transactions.
+    """
+    l1 = node_factory.get_node(1)
+    l1.fundwallet(10**4)
+
+    addr = l1.rpc.newaddr()["bech32"]
+    tx = l1.rpc.withdraw(addr, 10**3)["tx"]
+    nlocktime = node_factory.bitcoind.rpc.decoderawtransaction(tx)["locktime"]
+    tip = node_factory.bitcoind.rpc.getblockcount()
+
+    assert nlocktime > 0 and nlocktime <= tip
+
+
+@flaky
+@unittest.skipIf(VALGRIND, "A big loop is used to check fuzz.")
+def test_withdraw_nlocktime_fuzz(node_factory, bitcoind):
+    """
+    Test that we eventually fuzz nLockTime for withdrawal transactions.
+    Marked flaky "just in case" as we fuzz from 0 to 100 with a 10%
+    probability.
+    """
+    l1 = node_factory.get_node(1)
+    l1.fundwallet(10**8)
+
+    for i in range(100):
+        addr = l1.rpc.newaddr()["bech32"]
+        withdraw = l1.rpc.withdraw(addr, 10**3)
+        bitcoind.generate_block(1)
+        l1.daemon.wait_for_log('Owning output .* txid {} CONFIRMED'.
+                               format(withdraw["txid"]))
+        decoded = bitcoind.rpc.decoderawtransaction(withdraw["tx"])
+        tip = node_factory.bitcoind.rpc.getblockcount()
+        assert decoded["locktime"] > 0
+        if decoded["locktime"] < tip:
+            return
+    else:
+        raise Exception("No transaction with fuzzed nLockTime !")