txbatcher: if we raise NotEnoughFunds, remove

the largest output from the current tx and retry

In the unit test, this results in waiting until the current tx is mined.

electrum/txbatcher.py

@@ -439,10 +439,16 @@ class TxBatch(Logger):
                 to_sweep_now[k] = v
             else:
                 self.wallet.add_future_tx(v, wanted_height)
-        if not to_pay and not to_sweep_now and not self._should_bump_fee(base_tx):
-            return
         while True:
-            tx = self._create_batch_tx(base_tx, to_sweep_now, to_pay)
+            if not to_pay and not to_sweep_now and not self._should_bump_fee(base_tx):
+                return
+            try:
+                tx = self._create_batch_tx(base_tx, to_sweep_now, to_pay)
+            except NotEnoughFunds:
+                k = max(to_pay, key=lambda x: x.value)
+                self.logger.info(f'Not enough funds, removing output {k}')
+                to_pay.remove(k)
+                continue
             # 100 kb max standardness rule
             if tx.estimated_size() < 100_000:
                 break

tests/test_txbatcher.py

@@ -153,13 +153,21 @@ class TestTxBatcher(ElectrumTestCase):
         # to_self_payment tx1
         output1 = PartialTxOutput.from_address_and_value("tb1qyfnv3y866ufedugxxxfksyratv4pz3h78g9dad", 20_000)
         wallet.txbatcher.add_payment_output('default', output1, self.fee_policy_descriptor)
-        toself_tx = await self.network.next_tx()
-        assert len(toself_tx.outputs()) == 2
-        assert output1 in toself_tx.outputs()
+        tx1 = await self.network.next_tx()
+        assert len(tx1.outputs()) == 2
+        assert output1 in tx1.outputs()
 
         # outgoing payment tx2
         output2 = PartialTxOutput.from_address_and_value("tb1qkfn0fude7z789uys2u7sf80kd4805zpvs3na0h", 90_000)
         wallet.txbatcher.add_payment_output('default', output2, self.fee_policy_descriptor)
+        # before tx1 gets confirmed, txbatch.create_transaction will raise notenoughfunds
+        await asyncio.sleep(wallet.txbatcher.SLEEP_INTERVAL)
+
+        # tx1 gets confirmed
+        wallet.adb.receive_tx_callback(tx1, tx_height=1)
+        tx_mined_status = wallet.adb.get_tx_height(tx1.txid())
+        wallet.adb.add_verified_tx(tx1.txid(), tx_mined_status._replace(conf=1))
+
         tx2 = await self.network.next_tx()
         assert len(tx2.outputs()) == 2
         assert output2 in tx2.outputs()