tests: add plugin for simple invoice delay.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

tests/plugins/hold_invoice.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+"""Simple plugin to allow testing while closing of HTLC is delayed.
+"""
+
+from lightning import Plugin
+import time
+
+plugin = Plugin()
+
+
+@plugin.hook('invoice_payment')
+def on_payment(payment, plugin):
+    time.sleep(float(plugin.get_option('holdtime')))
+    return {}
+
+
+plugin.add_option('holdtime', '10', 'The time to hold invoice for.')
+plugin.run()

tests/test_plugin.py

@@ -2,7 +2,7 @@ from collections import OrderedDict
 from fixtures import *  # noqa: F401,F403
 from flaky import flaky  # noqa: F401
 from lightning import RpcError, Millisatoshi
-from utils import only_one, wait_for
+from utils import only_one, wait_for, TIMEOUT
 
 import os
 import pytest
@@ -293,6 +293,16 @@ def test_invoice_payment_hook(node_factory):
     l2.daemon.wait_for_log('preimage=' + '0' * 64)
 
 
+def test_invoice_payment_hook_hold(node_factory):
+    """ l1 uses the hold_invoice plugin to delay invoice payment.
+    """
+    opts = [{}, {'plugin': 'tests/plugins/hold_invoice.py', 'holdtime': TIMEOUT / 2}]
+    l1, l2 = node_factory.line_graph(2, opts=opts)
+
+    inv1 = l2.rpc.invoice(123000, 'label', 'description', preimage='1' * 64)
+    l1.rpc.pay(inv1['bolt11'])
+
+
 def test_openchannel_hook(node_factory, bitcoind):
     """ l2 uses the reject_odd_funding_amounts plugin to reject some openings.
     """