Fix lint; add test

Author: fselmo

hexbytes/main.py

@@ -3,7 +3,6 @@
     Callable,
     Tuple,
     Type,
-    TypeVar,
     Union,
     cast,
     overload,
@@ -18,8 +17,6 @@
         SupportsIndex,
     )
 
-_THexBytes = TypeVar("_THexBytes", bound="HexBytes")
-
 BytesLike = Union[bool, bytearray, bytes, int, str, memoryview]
 
 
@@ -65,15 +62,11 @@ def to_0x_hex(self) -> str:
         return "0x" + self.hex()
 
     def __reduce__(
-        self
-    ) -> Tuple[
-        Callable[[Type[_THexBytes], bytes], _THexBytes], 
-        Tuple[Type[_THexBytes], bytes],
-    ]:
+        self,
+    ) -> Tuple[Callable[..., bytes], Tuple[Type["HexBytes"], bytes]]:
         """
-        An optimized `__reduce__` that bypasses the input validation in `HexBytes.__new__`
-        since an existing HexBytes instance has already been validated when created.
-
-        This enables much faster unpickling of HexBytes objects.
+        An optimized ``__reduce__`` that bypasses the input validation in
+        ``HexBytes.__new__`` since an existing HexBytes instance has already been
+        validated when created.
         """
         return bytes.__new__, (type(self), bytes(self))

tests/core/test_hexbytes.py

@@ -1,4 +1,5 @@
 import pytest
+import pickle
 
 from eth_utils import (
     decode_hex,
@@ -125,3 +126,22 @@ def test_slice_stepped(primitive, start, stop, step):
         step = None
     expected = HexBytes(primitive[start:stop:step])
     assert hexbytes[start:stop:step] == expected
+
+
+def test_reduce_consistency():
+    obj = HexBytes(b"0x1234")
+
+    reduce_fn, reduce_args, *maybe_state = obj.__reduce__()
+
+    # recreate manually using reduce_fn
+    recreated = reduce_fn(*reduce_args)
+    if maybe_state:
+        recreated.__setstate__(maybe_state[0])
+
+    # check recreated instance equals original
+    assert recreated == obj  # or compare fields manually
+
+    dumped = pickle.dumps(obj)
+    loaded = pickle.loads(dumped)
+
+    assert loaded == obj