pytest: Change the channel persistence test to add inflight HTLCs

Now that we have HTLC persistence we'd also like to test it. This
kills the second node in the middle of an HTLC, it'll recover and
finish the flow.

Signed-off-by: Christian Decker <decker.christian@gmail.com>

tests/test_lightningd.py

@@ -1501,8 +1501,12 @@ class LightningDTests(BaseLightningDTests):
         assert outputs[2] == 10000000
 
     def test_channel_persistence(self):
-        # Start two nodes and open a channel (to remember)
-        l1, l2 = self.connect()
+        # Start two nodes and open a channel (to remember). l2 will
+        # mysteriously die while committing the first HTLC so we can
+        # check that HTLCs reloaded from the DB work.
+        l1 = self.node_factory.get_node()
+        l2 = self.node_factory.get_node(disconnect=['_WIRE_COMMITMENT_SIGNED'])
+        l1.rpc.connect('localhost', l2.info['port'], l2.info['id'])
 
         # Neither node should have a channel open, they are just connected
         for n in (l1, l2):
@@ -1517,13 +1521,18 @@ class LightningDTests(BaseLightningDTests):
         for n in (l1, l2):
             assert(n.db_query('SELECT COUNT(id) as count FROM channels;')[0]['count'] == 1)
 
-        # Perform a payment so we have something to restore
-        self.pay(l1, l2, 10000)
-        time.sleep(1)
-        assert l1.rpc.getpeers()['peers'][0]['msatoshi_to_us'] == 99990000
-        assert l2.rpc.getpeers()['peers'][0]['msatoshi_to_us'] == 10000
+        # Fire off a sendpay request, it'll get interrupted by a restart
+        fut = self.executor.submit(self.pay, l1, l2, 10000)
+        # Wait for it to be committed to, i.e., stored in the DB
+        l1.daemon.wait_for_log('peer_in WIRE_COMMITMENT_SIGNED')
+
         # Stop l2, l1 will reattempt to connect
-        l2.stop()
+        print("Killing l2 in mid HTLC")
+        l2.daemon.proc.terminate()
+
+        # Clear the disconnect and timer stop so we can proceed normally
+        l2.daemon.cmd_line = [e for e in l2.daemon.cmd_line if 'disconnect' not in e]
+        print(" ".join(l2.daemon.cmd_line + ['--dev-debugger=channeld']))
 
         # Wait for l1 to notice
         wait_for(lambda: not l1.rpc.getpeers()['peers'][0]['connected'])
@@ -1532,6 +1541,9 @@ class LightningDTests(BaseLightningDTests):
         l2.daemon.start()
         wait_for(lambda: len(l2.rpc.getpeers()['peers']) == 1)
 
+        # Wait for the restored HTLC to finish
+        wait_for(lambda: l1.rpc.getpeers()['peers'][0]['msatoshi_to_us'] == 99990000, interval=1)
+
         wait_for(lambda: len([p for p in l1.rpc.getpeers()['peers'] if p['connected']]), interval=1)
         wait_for(lambda: len([p for p in l2.rpc.getpeers()['peers'] if p['connected']]), interval=1)
 

tests/utils.py

@@ -235,7 +235,7 @@ class LightningD(TailableProc):
         ]
 
         self.cmd_line += ["--{}={}".format(k, v) for k, v in LIGHTNINGD_CONFIG.items()]
-        self.prefix = 'lightningd'
+        self.prefix = 'lightningd(%d)' % (port)
 
         if not os.path.exists(lightning_dir):
             os.makedirs(lightning_dir)