From f7cdf1dd989e2a03f97e791f5ec713a8785a414a Mon Sep 17 00:00:00 2001
From: Christian Decker <decker.christian@gmail.com>
Date: Wed, 9 Dec 2020 10:57:37 +0100
Subject: [PATCH] pytest: Debug test_lockup_drain

---
 contrib/pyln-testing/pyln/testing/utils.py | 7 +++++--
 tests/test_pay.py                          | 1 +
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/contrib/pyln-testing/pyln/testing/utils.py b/contrib/pyln-testing/pyln/testing/utils.py
index 2b88857ce..9ab4e1743 100644
--- a/contrib/pyln-testing/pyln/testing/utils.py
+++ b/contrib/pyln-testing/pyln/testing/utils.py
@@ -919,13 +919,16 @@ class LightningNode(object):
     # This helper sends all money to a peer until even 1 msat can't get through.
     def drain(self, peer):
         total = 0
-        msat = 16**9
+        msat = 4294967295  # Max payment size in some configs
         while msat != 0:
             try:
+                logging.debug("Drain step with size={}".format(msat))
                 self.pay(peer, msat)
                 total += msat
-            except RpcError:
+            except RpcError as e:
+                logging.debug("Got an exception while draining channel: {}".format(e))
                 msat //= 2
+        logging.debug("Draining complete after sending a total of {}msats".format(total))
         return total
 
     # Note: this feeds through the smoother in update_feerate, so changing
diff --git a/tests/test_pay.py b/tests/test_pay.py
index 944266f03..4f9b81bb8 100644
--- a/tests/test_pay.py
+++ b/tests/test_pay.py
@@ -2374,6 +2374,7 @@ def test_lockup_drain(node_factory, bitcoind):
     # But if feerate increase just a little more, l2 should not be able to send
     # non-fust HTLC to l1
     l1.force_feerates(30002)  # TODO: Why does 30001 fail? off by one in C code?
+    wait_for(lambda: l1.rpc.listpeers()['peers'][0]['connected'])
     with pytest.raises(RpcError, match=r".*Capacity exceeded.*"):
         l2.pay(l1, total // 2)