mmgen-txsend: add --test option

Test whether a transaction is sendable without sending it

- for BTC and friends, uses the ‘testmempoolaccept’ RPC call
- not implemented for ETH

mmgen/main_txsend.py

@@ -52,6 +52,7 @@ opts_data = {
 -q, --quiet      Suppress warnings; overwrite files without prompting
 -s, --status     Get status of a sent transaction (or current transaction,
                  whether sent or unsent, when used with --autosign)
+-t, --test       Test whether the transaction can be sent without sending it
 -v, --verbose    Be more verbose
 -y, --yes        Answer 'yes' to prompts, suppress non-essential output
 """
@@ -66,6 +67,9 @@ if cfg.autosign and cfg.outdir:
 if cfg.mark_sent and not cfg.autosign:
 	die(1, '--mark-sent is used only in combination with --autosign')
 
+if cfg.test and cfg.dump_hex:
+	die(1, '--test cannot be used in combination with --dump-hex')
+
 if cfg.dump_hex and cfg.dump_hex != '-':
 	from .fileutil import check_outfile_dir
 	check_outfile_dir(cfg.dump_hex)
@@ -158,6 +162,8 @@ async def main():
 				await post_send(tx)
 		else:
 			await post_send(tx)
+	elif cfg.test:
+		await tx.test_sendable()
 	elif await tx.send():
 		await post_send(tx)
 

mmgen/proto/btc/tx/online.py

@@ -13,13 +13,13 @@ proto.btc.tx.online: Bitcoin online signed transaction class
 """
 
 from ....tx import online as TxBase
-from ....util import msg, die
+from ....util import msg, ymsg, die
 from ....color import orange
 from .signed import Signed
 
 class OnlineSigned(Signed, TxBase.OnlineSigned):
 
-	async def send(self, *, prompt_user=True):
+	async def send_checks(self):
 
 		self.check_correct_chain()
 
@@ -37,6 +37,27 @@ class OnlineSigned(Signed, TxBase.OnlineSigned):
 
 		await self.status.display()
 
+	async def test_sendable(self):
+
+		await self.send_checks()
+
+		res = await self.rpc.call('testmempoolaccept', (self.serialized,))
+		ret = res[0]
+
+		if ret['allowed']:
+			from ....obj import CoinTxID
+			msg('TxID: {}'.format(CoinTxID(ret['txid']).hl()))
+			msg('Transaction can be sent')
+			return True
+		else:
+			ymsg('Transaction cannot be sent')
+			msg(ret['reject-reason'])
+			return False
+
+	async def send(self, *, prompt_user=True):
+
+		await self.send_checks()
+
 		if prompt_user:
 			self.confirm_send()
 

mmgen/proto/eth/tx/online.py

@@ -20,6 +20,9 @@ from .signed import Signed, TokenSigned
 
 class OnlineSigned(Signed, TxBase.OnlineSigned):
 
+	async def test_sendable(self):
+		raise NotImplementedError('transaction testing not implemented for Ethereum')
+
 	async def send(self, *, prompt_user=True):
 
 		self.check_correct_chain()

test/cmdtest_d/ct_regtest.py

@@ -465,6 +465,7 @@ class CmdTestRegtest(CmdTestBase, CmdTestShared):
 		('bob_dump_hex_sign',        'dump_hex transaction - signing'),
 		('bob_dump_hex_dump_stdout', 'dump_hex transaction - dumping tx hex to stdout'),
 		('bob_dump_hex_dump',        'dump_hex transaction - dumping tx hex to file'),
+		('bob_dump_hex_test',        'dump_hex transaction - test whether TX can be sent'),
 		('bob_dump_hex_send_cli',    'dump_hex transaction - sending via cli'),
 		('generate',                 'mining a block'),
 		('bob_bal7',                 'Bob’s balance'),
@@ -2241,6 +2242,12 @@ class CmdTestRegtest(CmdTestBase, CmdTestShared):
 		assert is_hex_str(txid) and len(txid) == 64
 		return t
 
+	def bob_dump_hex_test(self):
+		txfile = get_file_with_ext(self.dump_hex_subdir, 'sigtx')
+		t = self.spawn('mmgen-txsend', ['--bob', '--test', txfile])
+		self.txsend_ui_common(t, bogus_send=False, test=True)
+		return t
+
 	def bob_dump_hex_send_cli(self):
 		return self._user_dump_hex_send_cli('bob', subdir='nochg_tx')
 

test/cmdtest_d/ct_shared.py

@@ -162,6 +162,7 @@ class CmdTestShared:
 			file_desc    = 'Sent transaction',
 			confirm_send = True,
 			bogus_send   = True,
+			test         = False,
 			quiet        = False,
 			has_label    = False):
 
@@ -172,16 +173,19 @@ class CmdTestShared:
 			t.view_tx(view)
 			t.do_comment(add_comment, has_label=has_label)
 
-		self._do_confirm_send(t, quiet=quiet, confirm_send=confirm_send)
+		if not test:
+			self._do_confirm_send(t, quiet=quiet, confirm_send=confirm_send)
 
 		if bogus_send:
 			txid = ''
 			t.expect('BOGUS transaction NOT sent')
 		else:
-			txid = strip_ansi_escapes(t.expect_getend('Transaction sent: '))
+			m = 'TxID: ' if test else 'Transaction sent: '
+			txid = strip_ansi_escapes(t.expect_getend(m))
 			assert len(txid) == 64, f'{txid!r}: Incorrect txid length!'
 
-		t.written_to_file(file_desc)
+		if not test:
+			t.written_to_file(file_desc)
 
 		return txid