fix: preserve Wei and Gwei types in arithmetic

tests/core/types/test_currency_types.py

@@ -0,0 +1,37 @@
+from web3.types import (
+    Gwei,
+    Wei,
+)
+
+
+def test_wei_arithmetic_preserves_type() -> None:
+    value = Wei(5)
+
+    value += Wei(1)
+
+    assert value == 6
+    assert isinstance(value, Wei)
+    assert isinstance(value + 1, Wei)
+    assert isinstance(1 + value, Wei)
+    assert isinstance(value - 1, Wei)
+    assert isinstance(10 - value, Wei)
+    assert isinstance(value * 2, Wei)
+    assert isinstance(2 * value, Wei)
+    assert isinstance(value // 2, Wei)
+    assert isinstance(value % 4, Wei)
+    assert isinstance(-value, Wei)
+    assert isinstance(+value, Wei)
+    assert isinstance(abs(value), Wei)
+    quotient, remainder = divmod(value, 4)
+    assert isinstance(quotient, Wei)
+    assert isinstance(remainder, Wei)
+
+
+def test_gwei_arithmetic_preserves_type() -> None:
+    value = Gwei(5)
+
+    value -= Gwei(1)
+
+    assert value == 4
+    assert isinstance(value, Gwei)
+    assert isinstance(value + 1, Gwei)

web3/types.py

@@ -32,6 +32,7 @@
 )
 from web3._utils.compat import (
     NotRequired,
+    Self,
 )
 
 if TYPE_CHECKING:
@@ -76,8 +77,51 @@
 Nonce = NewType("Nonce", int)
 RPCEndpoint = NewType("RPCEndpoint", str)
 Timestamp = NewType("Timestamp", int)
-Wei = NewType("Wei", int)
-Gwei = NewType("Gwei", int)
+class _IntegerType(int):
+    def __add__(self, other: int) -> Self:
+        return self.__class__(int(self) + other)
+
+    def __radd__(self, other: int) -> Self:
+        return self.__class__(other + int(self))
+
+    def __sub__(self, other: int) -> Self:
+        return self.__class__(int(self) - other)
+
+    def __rsub__(self, other: int) -> Self:
+        return self.__class__(other - int(self))
+
+    def __mul__(self, other: int) -> Self:
+        return self.__class__(int(self) * other)
+
+    def __rmul__(self, other: int) -> Self:
+        return self.__class__(other * int(self))
+
+    def __floordiv__(self, other: int) -> Self:
+        return self.__class__(int(self) // other)
+
+    def __mod__(self, other: int) -> Self:
+        return self.__class__(int(self) % other)
+
+    def __divmod__(self, other: int) -> tuple[Self, Self]:
+        quotient, remainder = divmod(int(self), other)
+        return self.__class__(quotient), self.__class__(remainder)
+
+    def __neg__(self) -> Self:
+        return self.__class__(-int(self))
+
+    def __pos__(self) -> Self:
+        return self.__class__(+int(self))
+
+    def __abs__(self) -> Self:
+        return self.__class__(abs(int(self)))
+
+
+class Wei(_IntegerType):
+    pass
+
+
+class Gwei(_IntegerType):
+    pass
 Formatters = dict[RPCEndpoint, Callable[..., Any]]