feat: make dynamic structs pickleable with this one simple trick (#1990)

Co-authored-by: Juliya Smith <jules@apeworx.io>

src/ape/utils/abi.py

@@ -312,11 +312,11 @@ def contains(struct, key):
         return key in struct.__dataclass_fields__
 
     def is_equal(struct, other) -> bool:
-        _len = len(other)
         if not hasattr(other, "__len__"):
             return NotImplemented
 
-        elif _len != len(struct):
+        _len = len(other)
+        if _len != len(struct):
             return False
 
         if hasattr(other, "items"):
@@ -355,6 +355,9 @@ def items(struct) -> List[Tuple]:
     def values(struct) -> List[Any]:
         return [x[1] for x in struct.items()]
 
+    def reduce(struct) -> tuple:
+        return (create_struct, (name, types, output_values))
+
     # NOTE: Should never be "_{i}", but mypy complains and we need a unique value
     properties = [m.name or f"_{i}" for i, m in enumerate(types)]
     methods = {
@@ -363,6 +366,7 @@ def values(struct) -> List[Any]:
         "__setitem__": set_item,
         "__contains__": contains,
         "__len__": length,
+        "__reduce__": reduce,
         "items": items,
         "values": values,
     }

tests/functional/utils/test_abi.py

@@ -1,8 +1,11 @@
+import pickle
+from copy import deepcopy
+
 import pytest
 from eth_pydantic_types import HexBytes
-from ethpm_types.abi import EventABI, EventABIType
+from ethpm_types.abi import ABIType, EventABI, EventABIType
 
-from ape.utils.abi import LogInputABICollection
+from ape.utils.abi import LogInputABICollection, create_struct
 
 
 @pytest.fixture
@@ -79,3 +82,47 @@ def test_decoding_with_strict(collection, topics, log_data_missing_trailing_zero
         "stakingLimit": 0,
     }
     assert actual == expected
+
+
+class TestStruct:
+    @pytest.fixture
+    def struct(self):
+        return create_struct(
+            "MyStruct", (ABIType(name="proptest", type="string"),), ("output_value_0",)
+        )
+
+    def test_get_and_set_item(self, struct):
+        assert struct["proptest"] == "output_value_0"
+        struct["proptest"] = "something else"
+        assert struct["proptest"] == "something else"
+
+    def test_is_equal(self, struct):
+        # Show struct equality works when props are the same.
+        assert struct == struct  # even self
+        new_struct = deepcopy(struct)
+        assert struct == new_struct
+        # Show changing a property makes them unequal.
+        new_struct["proptest"] = "something else"
+        assert struct != new_struct
+        # Show testing with other types works w/o erroring.
+        assert struct != 47
+
+    def test_contains(self, struct):
+        assert "proptest" in struct
+
+    def test_len(self, struct):
+        assert len(struct) == 1
+
+    def test_items(self, struct):
+        actual = struct.items()
+        assert len(actual) == 1
+        assert actual[0] == ("proptest", "output_value_0")
+
+    def test_values(self, struct):
+        actual = struct.values()
+        assert len(actual) == 1
+        assert actual[0] == "output_value_0"
+
+    def test_pickle(self, struct):
+        actual = pickle.dumps(struct)
+        assert isinstance(actual, bytes)