pytest: Added a simple channel-persistence test

This test opens a channel, stops the nodes and the restarts them to
see if we can successfully reload the channel state from the database.

tests/test_lightningd.py

@@ -858,6 +858,35 @@ class LightningDTests(BaseLightningDTests):
         c.execute('SELECT COUNT(*) FROM outputs WHERE status=2')
         assert(c.fetchone()[0] == 2)
 
+    def test_channel_persistence(self):
+        # Start two nodes and open a channel (to remember)
+        l1, l2 = self.connect()
+
+        # Neither node should have a channel open, they are just connected
+        for n in (l1, l2):
+            assert(n.db_query('SELECT COUNT(id) as count FROM channels;')[0]['count'] == 0)
+
+        self.fund_channel(l1, l2, 100000)
+
+        peers = l1.rpc.getpeers()['peers']
+        assert(len(peers) == 1 and peers[0]['state'] == 'CHANNELD_NORMAL')
+
+        # Both nodes should now have exactly one channel in the database
+        for n in (l1, l2):
+            assert(n.db_query('SELECT COUNT(id) as count FROM channels;')[0]['count'] == 1)
+
+        l1.daemon.stop()
+
+        # Let the other side notice, then stop it
+        wait_for(lambda: not l2.rpc.getpeers()['peers'][0]['connected'])
+        l2.daemon.stop()
+
+        # Now restart l1 and it should reload peers/channels from the DB
+        l1.daemon.start()
+
+        #wait_for(lambda: len(l1.rpc.getpeers()['peers']) == 1)
+
+
 class LegacyLightningDTests(BaseLightningDTests):
 
     def test_connect(self):

tests/utils.py

@@ -42,8 +42,6 @@ class TailableProc(object):
     def __init__(self, outputDir=None):
         self.logs = []
         self.logs_cond = threading.Condition(threading.RLock())
-        self.thread = threading.Thread(target=self.tail)
-        self.thread.daemon = True
         self.cmd_line = None
         self.running = False
         self.proc = None
@@ -55,6 +53,8 @@ class TailableProc(object):
         """
         logging.debug("Starting '%s'", " ".join(self.cmd_line))
         self.proc = subprocess.Popen(self.cmd_line, stdout=subprocess.PIPE)
+        self.thread = threading.Thread(target=self.tail)
+        self.thread.daemon = True
         self.thread.start()
         self.running = True