pytest: test the invoice hook.

Signed-off-by: Rusty Russell <[email protected]>

tests/plugins/reject_some_invoices.py

@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+"""Simple plugin to test the invoice_payment_hook.
+
+We just refuse to let them pay invoices with preimages divisible by 16.
+"""
+
+from lightning import Plugin
+
+plugin = Plugin()
+
+
+@plugin.hook('invoice_payment')
+def on_payment(payment, plugin):
+    print("label={}".format(payment['label']))
+    print("msat={}".format(payment['msat']))
+    print("preimage={}".format(payment['preimage']))
+
+    if payment['preimage'].endswith('0'):
+        # FIXME: Define this!
+        WIRE_TEMPORARY_NODE_FAILURE = 0x2002
+        return {'result': {'failure_code': WIRE_TEMPORARY_NODE_FAILURE}}
+
+    return {'result': {}}
+
+
+plugin.run()

tests/test_plugin.py

@@ -233,3 +233,30 @@ def test_utf8_passthrough(node_factory, executor):
                                    'utf8', 'ナンセンス 1杯']).decode('utf-8')
     assert '\\u' not in out
     assert out == '{\n   "utf8" : "ナンセンス 1杯"\n}\n'
+
+
+def test_invoice_payment_hook(node_factory):
+    """ l1 uses the reject-payment plugin to reject invoices with odd preimages.
+    """
+    opts = [{}, {'plugin': 'tests/plugins/reject_some_invoices.py'}]
+    l1, l2 = node_factory.line_graph(2, opts=opts)
+
+    # This one works
+    inv1 = l2.rpc.invoice(123000, 'label', 'description', preimage='1' * 64)
+    l1.rpc.pay(inv1['bolt11'])
+
+    l2.daemon.wait_for_log('label=label')
+    l2.daemon.wait_for_log('msat=')
+    l2.daemon.wait_for_log('preimage=' + '1' * 64)
+
+    # This one will be rejected.
+    inv2 = l2.rpc.invoice(123000, 'label2', 'description', preimage='0' * 64)
+    with pytest.raises(RpcError):
+        l1.rpc.pay(inv2['bolt11'])
+
+    pstatus = l1.rpc.call('paystatus', [inv2['bolt11']])['pay'][0]
+    assert pstatus['attempts'][0]['failure']['data']['failcodename'] == 'WIRE_TEMPORARY_NODE_FAILURE'
+
+    l2.daemon.wait_for_log('label=label2')
+    l2.daemon.wait_for_log('msat=')
+    l2.daemon.wait_for_log('preimage=' + '0' * 64)