From 58c624d067419989b30e532d24362fd2faa16780 Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Wed, 12 Apr 2023 14:22:15 +0930
Subject: [PATCH] pytest: fix test_penalty_htlc_tx_timeout accounting flake.

This test makes l2 save db, make a payment, then rollback.
*Sometimes* under CI (but not here) we don't shutdown fast enough
after the payment, so the moves.json from the coin_movements.py
records it.  Sure enough, the result is the node ends up with
a -10000msat balance.

Validated by putting a time.sleep(5) between:

```
    l2.rpc.pay(inv['bolt11'])

    import time
    time.sleep(5)
    # stop both nodes, roll back l2's database
```

The answer, of course, is to save and rollback *both* the db and
moves.json file.

Here's the error:
```
    def test_penalty_htlc_tx_timeout(node_factory, bitcoind, chainparams):
...
        assert account_balance(l3, channel_id) == 0
>       assert account_balance(l2, channel_id) == 0

tests/test_closing.py:1527:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
tests/utils.py:184: in account_balance
    m_sum -= Millisatoshi(m['debit_msat'])
contrib/pyln-client/pyln/client/lightning.py:197: in __sub__
    return Millisatoshi(int(self) - int(other))
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = -10000msat, v = -10000
...
        if self.millisatoshis < 0:
>           raise ValueError("Millisatoshi must be >= 0")
E           ValueError: Millisatoshi must be >= 0

contrib/pyln-client/pyln/client/lightning.py:82: ValueError
```

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 tests/test_closing.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tests/test_closing.py b/tests/test_closing.py
index a58a5189a..022daf2fc 100644
--- a/tests/test_closing.py
+++ b/tests/test_closing.py
@@ -1435,6 +1435,10 @@ def test_penalty_htlc_tx_timeout(node_factory, bitcoind, chainparams):
     l2_db_path = os.path.join(l2.daemon.lightning_dir, chainparams['name'], 'lightningd.sqlite3')
     l2_db_path_bak = os.path.join(l2.daemon.lightning_dir, chainparams['name'], 'lightningd.sqlite3.bak')
     copyfile(l2_db_path, l2_db_path_bak)
+    # make snapshot of l2 moves accounting too!
+    l2_moves_path = os.path.join(l2.daemon.lightning_dir, chainparams['name'], 'moves.json')
+    l2_moves_path_bak = os.path.join(l2.daemon.lightning_dir, chainparams['name'], 'moves.json.bak')
+    copyfile(l2_moves_path, l2_moves_path_bak)
     l2.start()
     sync_blockheight(bitcoind, [l2])
 
@@ -1450,6 +1454,7 @@ def test_penalty_htlc_tx_timeout(node_factory, bitcoind, chainparams):
     l2.stop()
     l3.stop()
     copyfile(l2_db_path_bak, l2_db_path)
+    copyfile(l2_moves_path_bak, l2_moves_path)
 
     # start l2, now back a bit. force close channel with l3 while l3 is still offline
     l2.start()