test: refactor: remove hex_str_to_bytes helper

Use the built-in class method bytes.fromhex() instead,
which is available since Python 3.0.

test/functional/test_framework/address.py

@@ -12,7 +12,7 @@ import unittest
 
 from .script import hash256, hash160, sha256, CScript, OP_0
 from .segwit_addr import encode_segwit_address
-from .util import assert_equal, hex_str_to_bytes
+from .util import assert_equal
 
 ADDRESS_BCRT1_UNSPENDABLE = 'bcrt1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq3xueyj'
 ADDRESS_BCRT1_UNSPENDABLE_DESCRIPTOR = 'addr(bcrt1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq3xueyj)#juyq9d97'
@@ -33,7 +33,7 @@ def byte_to_base58(b, version):
     result = ''
     str = b.hex()
     str = chr(version).encode('latin-1').hex() + str
-    checksum = hash256(hex_str_to_bytes(str)).hex()
+    checksum = hash256(bytes.fromhex(str)).hex()
     str += checksum[:8]
     value = int('0x' + str, 0)
     while value > 0:
@@ -100,7 +100,7 @@ def key_to_p2sh_p2wpkh(key, main=False):
 
 def program_to_witness(version, program, main=False):
     if (type(program) is str):
-        program = hex_str_to_bytes(program)
+        program = bytes.fromhex(program)
     assert 0 <= version <= 16
     assert 2 <= len(program) <= 40
     assert version > 0 or len(program) in [20, 32]
@@ -121,14 +121,14 @@ def script_to_p2sh_p2wsh(script, main=False):
 
 def check_key(key):
     if (type(key) is str):
-        key = hex_str_to_bytes(key)  # Assuming this is hex string
+        key = bytes.fromhex(key)  # Assuming this is hex string
     if (type(key) is bytes and (len(key) == 33 or len(key) == 65)):
         return key
     assert False
 
 def check_script(script):
     if (type(script) is str):
-        script = hex_str_to_bytes(script)  # Assuming this is hex string
+        script = bytes.fromhex(script)  # Assuming this is hex string
     if (type(script) is bytes or type(script) is CScript):
         return script
     assert False