improve currency fix (#269)

* improve currency fix

* improve currency fix

* improve currency fix

* fix tests

* fix types

* respond to comments

* remove extraneous maxDiff in test

Co-authored-by: Mayukha Vadari <mvadari@ripple.com>

Author: ledhed2222

tests/unit/models/currencies/test_issued_currency.py

@@ -15,12 +15,12 @@ def test_correct_currency_code_format(self):
         self.assertTrue(obj.is_valid())
 
     def test_correct_lower_currency_code_format(self):
-        # lower case is discouraged but allowed
-        obj = IssuedCurrency(
-            currency="usd",
-            issuer=_ACCOUNT,
-        )
-        self.assertTrue(obj.is_valid())
+        # lower case is not allowed
+        with self.assertRaises(XRPLModelException):
+            IssuedCurrency(
+                currency="usd",
+                issuer=_ACCOUNT,
+            )
 
     def test_incorrect_currency_code_format(self):
         # the "+" is not allowed in a currency format"

xrpl/constants.py

@@ -1,5 +1,9 @@
 """Collection of public constants for XRPL."""
 from enum import Enum
+from re import compile
+from typing import Pattern
+
+from typing_extensions import Final
 
 
 class CryptoAlgorithm(str, Enum):
@@ -13,3 +17,14 @@ class XRPLException(Exception):
     """Base Exception for XRPL library."""
 
     pass
+
+
+ISO_CURRENCY_REGEX: Final[Pattern[str]] = compile("^[A-Z0-9]{3}$")
+"""
+:meta private:
+"""
+
+HEX_CURRENCY_REGEX: Final[Pattern[str]] = compile("^[A-F0-9]{40}$")
+"""
+:meta private:
+"""

xrpl/core/binarycodec/types/currency.py

@@ -1,22 +1,20 @@
 """Codec for currency property inside an XRPL issued currency amount json."""
 from __future__ import annotations  # Requires Python 3.7+
 
-import re
 from typing import Optional, Type
 
 from typing_extensions import Final
 
+from xrpl.constants import HEX_CURRENCY_REGEX, ISO_CURRENCY_REGEX
 from xrpl.core.binarycodec.exceptions import XRPLBinaryCodecException
 from xrpl.core.binarycodec.types.hash160 import Hash160
 
-_ISO_REGEX: Final[re.Pattern[str]] = re.compile("^[A-Z0-9]{3}$")
-_HEX_REGEX: Final[re.Pattern[str]] = re.compile("^[A-F0-9]{40}$")
 _CURRENCY_CODE_LENGTH: Final[int] = 20  # bytes
 
 
 def _is_iso_code(value: str) -> bool:
     """Tests if value is a valid 3-char iso code."""
-    return bool(_ISO_REGEX.fullmatch(value))
+    return bool(ISO_CURRENCY_REGEX.fullmatch(value))
 
 
 def _iso_code_from_hex(value: bytes) -> Optional[str]:
@@ -33,7 +31,7 @@ def _iso_code_from_hex(value: bytes) -> Optional[str]:
 
 def _is_hex(value: str) -> bool:
     """Tests if value is a valid 40-char hex string."""
-    return bool(_HEX_REGEX.fullmatch(value))
+    return bool(HEX_CURRENCY_REGEX.fullmatch(value))
 
 
 def _iso_to_bytes(iso: str) -> bytes:
@@ -85,7 +83,7 @@ def __init__(self: Currency, buffer: Optional[bytes] = None) -> None:
         code_bytes = self.buffer[12:15]
         # Determine whether this currency code is in standard or nonstandard format:
         # https://xrpl.org/currency-formats.html#nonstandard-currency-codes
-        if self.buffer[:2] != bytes(2):
+        if self.buffer[0] != 0:
             # non-standard currency
             self._iso = None
         elif code_bytes.hex() == "000000":

xrpl/models/currencies/issued_currency.py

@@ -6,22 +6,20 @@
 """
 from __future__ import annotations
 
-import re
 from dataclasses import dataclass
 from typing import Dict
 
-from typing_extensions import Final
-
+from xrpl.constants import HEX_CURRENCY_REGEX, ISO_CURRENCY_REGEX
 from xrpl.models.base_model import BaseModel
 from xrpl.models.required import REQUIRED
 from xrpl.models.utils import require_kwargs_on_init
 
-_CHAR: Final[str] = r"[A-Za-z\d\?!@#\$%\^&\*<>\(\){}\[\]\|]"
-_CURRENCY_CODE: Final[str] = f"{_CHAR}{{3}}"
-_HEX: Final[str] = f"{_CHAR}{{40}}"
-_VALIDATOR: Final[re.Pattern[str]] = re.compile(
-    f"(?:{_CURRENCY_CODE}|{_HEX})",
-)
+
+def _is_valid_currency(candidate: str) -> bool:
+    return bool(
+        ISO_CURRENCY_REGEX.fullmatch(candidate)
+        or HEX_CURRENCY_REGEX.fullmatch(candidate)
+    )
 
 
 @require_kwargs_on_init
@@ -52,6 +50,6 @@ def _get_errors(self: IssuedCurrency) -> Dict[str, str]:
         errors = super()._get_errors()
         if self.currency.upper() == "XRP":
             errors["currency"] = "Currency must not be XRP for issued currency"
-        elif not _VALIDATOR.fullmatch(self.currency):
+        elif not _is_valid_currency(self.currency):
             errors["currency"] = f"Invalid currency {self.currency}"
         return errors