test: refactor: introduce `generate_keypair` helper with WIF support

In functional tests it is a quite common scenario to generate fresh
elliptic curve keypairs, which is currently a bit cumbersome as it
involves multiple steps, e.g.:

    privkey = ECKey()
    privkey.generate()
    privkey_wif = bytes_to_wif(privkey.get_bytes())
    pubkey = privkey.get_pubkey().get_bytes()

Simplify this by providing a new `generate_keypair` helper function that
returns the private key either as `ECKey` object or as WIF-string
(depending on the boolean `wif` parameter) and the public key as
byte-string; these formats are what we mostly need (currently we don't
use `ECPubKey` objects from generated keypairs anywhere).

With this, most of the affected code blocks following the pattern above
can be replaced by one-liners, e.g.:

    privkey, pubkey = generate_keypair(wif=True)

Note that after this commit, the only direct uses of `ECKey` remain in
situations where we want to set the private key explicitly, e.g. in
MiniWallet (test/functional/test_framework/wallet.py) or the test for
the signet miner script (test/functional/tool_signet_miner.py).

1 files changed, 7 insertions, 14 deletions

diff --git a/test/functional/rpc_signrawtransactionwithkey.py b/test/functional/rpc_signrawtransactionwithkey.py
index 580f63063d..ac7a86704f 100755
--- a/test/functional/rpc_signrawtransactionwithkey.py
+++ b/test/functional/rpc_signrawtransactionwithkey.py
@@ -11,7 +11,6 @@ from test_framework.address import (
     address_to_scriptpubkey,
     script_to_p2sh,
 )
-from test_framework.key import ECKey
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
@@ -23,16 +22,16 @@ from test_framework.script_util import (
     script_to_p2sh_p2wsh_script,
     script_to_p2wsh_script,
 )
+from test_framework.wallet import (
+    getnewdestination,
+)
 from test_framework.wallet_util import (
-    bytes_to_wif,
+    generate_keypair,
 )
 
 from decimal import (
     Decimal,
 )
-from test_framework.wallet import (
-    getnewdestination,
-)
 
 
 class SignRawTransactionWithKeyTest(BitcoinTestFramework):
@@ -80,11 +79,8 @@ class SignRawTransactionWithKeyTest(BitcoinTestFramework):
     def witness_script_test(self):
         self.log.info("Test signing transaction to P2SH-P2WSH addresses without wallet")
         # Create a new P2SH-P2WSH 1-of-1 multisig address:
-        eckey = ECKey()
-        eckey.generate()
-        embedded_privkey = bytes_to_wif(eckey.get_bytes())
-        embedded_pubkey = eckey.get_pubkey().get_bytes().hex()
-        p2sh_p2wsh_address = self.nodes[1].createmultisig(1, [embedded_pubkey], "p2sh-segwit")
+        embedded_privkey, embedded_pubkey = generate_keypair(wif=True)
+        p2sh_p2wsh_address = self.nodes[1].createmultisig(1, [embedded_pubkey.hex()], "p2sh-segwit")
         # send transaction to P2SH-P2WSH 1-of-1 multisig address
         self.block_hash = self.generate(self.nodes[0], COINBASE_MATURITY + 1)
         self.blk_idx = 0
@@ -109,10 +105,7 @@ class SignRawTransactionWithKeyTest(BitcoinTestFramework):
 
     def verify_txn_with_witness_script(self, tx_type):
         self.log.info("Test with a {} script as the witnessScript".format(tx_type))
-        eckey = ECKey()
-        eckey.generate()
-        embedded_privkey = bytes_to_wif(eckey.get_bytes())
-        embedded_pubkey = eckey.get_pubkey().get_bytes().hex()
+        embedded_privkey, embedded_pubkey = generate_keypair(wif=True)
         witness_script = {
             'P2PKH': key_to_p2pkh_script(embedded_pubkey).hex(),
             'P2PK': key_to_p2pk_script(embedded_pubkey).hex()