Merge bitcoin/bitcoin#22257: test: refactor: various (de)serialization helpers cleanups/improvements

bdb8b9a347e68f80a2e8d44ce5590a2e8214b6bb test: doc: improve doc for `from_hex` helper (mention `to_hex` alternative) (Sebastian Falbesoner)
191405420815d49ab50184513717a303fc2744d6 scripted-diff: test: rename `FromHex` to `from_hex` (Sebastian Falbesoner)
a79396fe5f8f81c78cf84117a87074c6ff6c9d95 test: remove `ToHex` helper, use .serialize().hex() instead (Sebastian Falbesoner)
2ce7b47958c4a10ba20dc86c011d71cda4b070a5 test: introduce `tx_from_hex` helper for tx deserialization (Sebastian Falbesoner)

Pull request description:

  There are still many functional tests that perform conversions from a hex-string to a message object (deserialization) manually. This PR identifies all those instances and replaces them with a newly introduced helper `tx_from_hex`.

  Instances were found via
  * `git grep "deserialize.*BytesIO"`

  and some of them manually, when it were not one-liners.

  Further, the helper `ToHex` was removed and simply replaced by `.serialize().hex()`, since now both variants are in use (sometimes even within the same test) and using the helper doesn't really have an advantage in readability. (see discussion https://github.com/bitcoin/bitcoin/pull/22257#discussion_r652404782)

ACKs for top commit:
  MarcoFalke:
    review re-ACK bdb8b9a347e68f80a2e8d44ce5590a2e8214b6bb 😁

Tree-SHA512: e25d7dc85918de1d6755a5cea65471b07a743204c20ad1c2f71ff07ef48cc1b9ad3fe5f515c1efaba2b2e3d89384e7980380c5d81895f9826e2046808cd3266e

1 files changed, 9 insertions, 9 deletions

diff --git a/test/functional/rpc_rawtransaction.py b/test/functional/rpc_rawtransaction.py
index 53ddf24e47..db57368eae 100755
--- a/test/functional/rpc_rawtransaction.py
+++ b/test/functional/rpc_rawtransaction.py
@@ -14,16 +14,17 @@ Test the following RPCs:
 
 from collections import OrderedDict
 from decimal import Decimal
-from io import BytesIO
 
 from test_framework.blocktools import COINBASE_MATURITY
-from test_framework.messages import CTransaction, ToHex
+from test_framework.messages import (
+    CTransaction,
+    tx_from_hex,
+)
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
     assert_raises_rpc_error,
     find_vout_for_address,
-    hex_str_to_bytes,
 )
 
 
@@ -127,23 +128,22 @@ class RawTransactionsTest(BitcoinTestFramework):
         assert_raises_rpc_error(-3, "Expected type bool", self.nodes[0].createrawtransaction, [], {}, 0, 'foo')
 
         self.log.info('Check that createrawtransaction accepts an array and object as outputs')
-        tx = CTransaction()
         # One output
-        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs={address: 99}))))
+        tx = tx_from_hex(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs={address: 99}))
         assert_equal(len(tx.vout), 1)
         assert_equal(
             tx.serialize().hex(),
             self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{address: 99}]),
         )
         # Two outputs
-        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=OrderedDict([(address, 99), (address2, 99)])))))
+        tx = tx_from_hex(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=OrderedDict([(address, 99), (address2, 99)])))
         assert_equal(len(tx.vout), 2)
         assert_equal(
             tx.serialize().hex(),
             self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=[{address: 99}, {address2: 99}]),
         )
         # Multiple mixed outputs
-        tx.deserialize(BytesIO(hex_str_to_bytes(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=multidict([(address, 99), (address2, 99), ('data', '99')])))))
+        tx = tx_from_hex(self.nodes[2].createrawtransaction(inputs=[{'txid': txid, 'vout': 9}], outputs=multidict([(address, 99), (address2, 99), ('data', '99')])))
         assert_equal(len(tx.vout), 3)
         assert_equal(
             tx.serialize().hex(),
@@ -450,14 +450,14 @@ class RawTransactionsTest(BitcoinTestFramework):
         # As transaction version is unsigned, this should convert to its unsigned equivalent.
         tx = CTransaction()
         tx.nVersion = -0x80000000
-        rawtx = ToHex(tx)
+        rawtx = tx.serialize().hex()
         decrawtx = self.nodes[0].decoderawtransaction(rawtx)
         assert_equal(decrawtx['version'], 0x80000000)
 
         # Test the maximum transaction version number that fits in a signed 32-bit integer.
         tx = CTransaction()
         tx.nVersion = 0x7fffffff
-        rawtx = ToHex(tx)
+        rawtx = tx.serialize().hex()
         decrawtx = self.nodes[0].decoderawtransaction(rawtx)
         assert_equal(decrawtx['version'], 0x7fffffff)