Merge #897: Fix additionalfeeoutputindex check in BIP78

c70f253 add test case for low feerate (Adam Gibson)
15089fc Fix additionalfeeoutputindex check in BIP78 (Adam Gibson)

jmclient/jmclient/payjoin.py

@@ -735,7 +735,7 @@ class PayjoinConverter(object):
             return (False, "Invalid request parameters.",
                               "original-psbt-rejected")
 
-        if afoi and not (self.manager.change_out_index == afoi):
+        if afoi is not None and not (self.manager.change_out_index == afoi):
             return (False, "additionalfeeoutputindex is "
                                     "not the change output. Joinmarket does "
                                     "not currently support this.",
@@ -817,7 +817,7 @@ class PayjoinConverter(object):
         # set the intended virtual size of our input:
         vsize = self.manager.get_vsize_for_input()
         our_fee_bump = 0
-        if afoi:
+        if afoi is not None:
             # We plan to reduce the change_out by a fee contribution.
             # Calculate the additional fee we think we need for our input,
             # to keep the same feerate as the original transaction (this also

jmclient/test/test_payjoin.py

@@ -145,6 +145,16 @@ class TrialTestPayjoin3(PayjoinTestBase, unittest.TestCase):
         self.wallet_structure = [3, 1, 0, 0, 0]
         return self.do_test_payment(SegwitWallet, SegwitWallet, amt=4.5)
 
+class TrialTestPayjoin4(PayjoinTestBase, unittest.TestCase):
+    def reset_fee(self, res):
+        jm_single().config.set("POLICY", "txfees", self.old_txfees)
+    def test_low_feerate(self):
+        self.old_txfees = jm_single().config.get("POLICY", "tx_fees")
+        jm_single().config.set("POLICY", "tx_fees", "1300")
+        d = self.do_test_payment(SegwitWallet, SegwitWallet)
+        d.addCallback(self.reset_fee)
+        return d
+
 def bip78_receiver_response(response, manager):
     d = readBody(response)
     # if the response code is not 200 OK, we must assume payjoin