Attempt to improve liskov substitution principle error (Python-Cardano#128)

* UPDATE. including network.py module in mypy test

* UPDATE: bump mypy version

UPDATE: include serialization.py in mypy test

UPDATE: Primitive is a union type now

UPDATE: f-string formatted values are explicitly converted into strings

REMOVE: field_sorter() had no real usage

UPDATE: from_primitive() takes a generalized Primitive value

UPDATE: narrow Primitive value type within from_primitive()

FIX: BlockFrostChainContext constructor to have an empty string default value

* ADD. adding network.py module unittests for better coverage

Author: daehan-koreapool

poetry.lock

@@ -49,7 +49,7 @@ class BlockFrostChainContext(ChainContext):
     _protocol_param: Optional[ProtocolParameters] = None
 
     def __init__(
-        self, project_id: str, network: Network = Network.TESTNET, base_url: str = None
+        self, project_id: str, network: Network = Network.TESTNET, base_url: str = ""
     ):
         self._network = network
         self._project_id = project_id

pycardano/backend/blockfrost.py

@@ -5,7 +5,8 @@
 from enum import Enum
 from typing import Type
 
-from pycardano.serialization import CBORSerializable
+from pycardano.exception import DeserializeException
+from pycardano.serialization import CBORSerializable, Primitive
 
 __all__ = ["Network"]
 
@@ -22,5 +23,9 @@ def to_primitive(self) -> int:
         return self.value
 
     @classmethod
-    def from_primitive(cls: Type[Network], value: int) -> Network:
+    def from_primitive(cls: Type[Network], value: Primitive) -> Network:
+        if not isinstance(value, int):
+            raise DeserializeException(
+                f"An integer value is required for deserialization: {str(value)}"
+            )
         return cls(value)

pycardano/network.py

@@ -9,7 +9,7 @@
 from datetime import datetime
 from decimal import Decimal
 from inspect import isclass
-from typing import Any, Callable, ClassVar, List, Type, TypeVar, Union, get_type_hints
+from typing import Any, Callable, List, Type, TypeVar, Union, get_type_hints
 
 from cbor2 import CBOREncoder, CBORSimpleValue, CBORTag, dumps, loads, undefined
 from pprintpp import pformat
@@ -53,8 +53,31 @@ class RawCBOR:
     cbor: bytes
 
 
-Primitive = TypeVar(
-    "Primitive",
+Primitive = Union[
+    bytes,
+    bytearray,
+    str,
+    int,
+    float,
+    Decimal,
+    bool,
+    None,
+    tuple,
+    list,
+    IndefiniteList,
+    dict,
+    defaultdict,
+    OrderedDict,
+    undefined.__class__,
+    datetime,
+    re.Pattern,
+    CBORSimpleValue,
+    CBORTag,
+    set,
+    frozenset,
+]
+
+PRIMITIVE_TYPES = (
     bytes,
     bytearray,
     str,
@@ -381,10 +404,10 @@ def _restore_dataclass_field(
                     return t.from_primitive(v)
                 except DeserializeException:
                     pass
-            elif t in Primitive.__constraints__ and isinstance(v, t):
+            elif t in PRIMITIVE_TYPES and isinstance(v, t):
                 return v
         raise DeserializeException(
-            f"Cannot deserialize object: \n{v}\n in any valid type from {t_args}."
+            f"Cannot deserialize object: \n{str(v)}\n in any valid type from {t_args}."
         )
     return v
 
@@ -453,8 +476,6 @@ class ArrayCBORSerializable(CBORSerializable):
         Test2(c='c', test1=Test1(a='a', b=None))
     """
 
-    field_sorter: ClassVar[Callable[[List], List]] = lambda x: x
-
     def to_shallow_primitive(self) -> List[Primitive]:
         """
         Returns:
@@ -465,15 +486,15 @@ def to_shallow_primitive(self) -> List[Primitive]:
                 types.
         """
         primitives = []
-        for f in self.__class__.field_sorter(fields(self)):
+        for f in fields(self):
             val = getattr(self, f.name)
             if val is None and f.metadata.get("optional"):
                 continue
             primitives.append(val)
         return primitives
 
     @classmethod
-    def from_primitive(cls: Type[ArrayBase], values: List[Primitive]) -> ArrayBase:
+    def from_primitive(cls: Type[ArrayBase], values: Primitive) -> ArrayBase:
         """Restore a primitive value to its original class type.
 
         Args:
@@ -660,7 +681,7 @@ def __init__(self, *args, **kwargs):
     def __getattr__(self, item):
         return getattr(self.data, item)
 
-    def __setitem__(self, key: KEY_TYPE, value: VALUE_TYPE):
+    def __setitem__(self, key: Any, value: Any):
         check_type("key", key, self.KEY_TYPE)
         check_type("value", value, self.VALUE_TYPE)
         self.data[key] = value
@@ -704,7 +725,7 @@ def _get_sortable_val(key):
         return dict(sorted(self.data.items(), key=lambda x: _get_sortable_val(x[0])))
 
     @classmethod
-    def from_primitive(cls: Type[DictBase], value: dict) -> DictBase:
+    def from_primitive(cls: Type[DictBase], value: Primitive) -> DictBase:
         """Restore a primitive value to its original class type.
 
         Args:
@@ -718,13 +739,17 @@ def from_primitive(cls: Type[DictBase], value: dict) -> DictBase:
             DeserializeException: When the object could not be restored from primitives.
         """
         if not value:
-            raise DeserializeException(f"Cannot accept empty value {value}.")
+            raise DeserializeException(f"Cannot accept empty value {str(value)}.")
+        if not isinstance(value, dict):
+            raise DeserializeException(
+                f"A dictionary value is required for deserialization: {str(value)}"
+            )
+
         restored = cls()
         for k, v in value.items():
             k = (
                 cls.KEY_TYPE.from_primitive(k)
-                if isclass(cls.VALUE_TYPE)
-                and issubclass(cls.KEY_TYPE, CBORSerializable)
+                if isclass(cls.KEY_TYPE) and issubclass(cls.KEY_TYPE, CBORSerializable)
                 else k
             )
             v = (
@@ -736,13 +761,13 @@ def from_primitive(cls: Type[DictBase], value: dict) -> DictBase:
             restored[k] = v
         return restored
 
-    def copy(self) -> DictBase:
+    def copy(self) -> DictCBORSerializable:
         return self.__class__(self)
 
 
 @typechecked
 def list_hook(
-    cls: Type[CBORSerializable],
+    cls: Type[CBORBase],
 ) -> Callable[[List[Primitive]], List[CBORBase]]:
     """A factory that generates a Callable which turns a list of Primitive to a list of CBORSerializables.
 

pycardano/serialization.py

@@ -44,7 +44,7 @@ sphinx-copybutton = "^0.5.0"
 retry = "^0.9.2"
 Flask = "^2.0.3"
 pytest-xdist = "^3.0.2"
-mypy = "^0.982"
+mypy = "^0.990"
 
 [build-system]
 requires = ["poetry-core>=1.0.0"]
@@ -76,9 +76,7 @@ exclude = [
     '^pycardano/logging.py$',
     '^pycardano/metadata.py$',
     '^pycardano/nativescript.py$',
-    '^pycardano/network.py$',
     '^pycardano/plutus.py$',
-    '^pycardano/serialization.py$',
     '^pycardano/transaction.py$',
     '^pycardano/txbuilder.py$',
     '^pycardano/utils.py$',

pyproject.toml

@@ -0,0 +1,32 @@
+import pytest
+
+from pycardano.exception import DeserializeException
+from pycardano.network import Network
+
+
+def test_from_primitive_invalid_primitive_input():
+    value = "a string value"
+    with pytest.raises(DeserializeException):
+        Network.from_primitive(value)
+
+
+def test_from_primitive_testnet():
+    testnet_value = 0
+    network = Network.from_primitive(testnet_value)
+    assert network.value == testnet_value
+
+
+def test_from_primitive_mainnet():
+    mainnet_value = 1
+    network = Network.from_primitive(mainnet_value)
+    assert network.value == mainnet_value
+
+
+def test_to_primitive_testnet():
+    network = Network(0)
+    assert network.to_primitive() == 0
+
+
+def test_to_primitive_mainnet():
+    network = Network(1)
+    assert network.to_primitive() == 1