match_object() - Improve serialization for properties/iterators/enums (#17)

Author: bblommers

localstack_snapshot/snapshots/prototype.py

@@ -2,7 +2,9 @@
 import json
 import logging
 import os
+from collections.abc import Iterator
 from datetime import datetime, timezone
+from enum import Enum
 from json import JSONDecodeError
 from pathlib import Path
 from re import Pattern
@@ -169,16 +171,27 @@ def _update(self, key: str, obj_state: dict) -> None:
     def match_object(self, key: str, obj: object) -> None:
         def _convert_object_to_dict(obj_):
             if isinstance(obj_, dict):
-                for key in list(obj_.keys()):
-                    if key.startswith("_"):
-                        del obj_[key]
-                    else:
-                        obj_[key] = _convert_object_to_dict(obj_[key])
-            elif isinstance(obj_, list):
-                for idx, val in enumerate(obj_):
-                    obj_[idx] = _convert_object_to_dict(val)
+                # Serialize the values of the dictionary, while skipping any private keys (starting with '_')
+                return {
+                    key_: _convert_object_to_dict(obj_[key_])
+                    for key_ in obj_
+                    if not key_.startswith("_")
+                }
+            elif isinstance(obj_, (list, Iterator)):
+                return [_convert_object_to_dict(val) for val in obj_]
+            elif isinstance(obj_, Enum):
+                return obj_.value
             elif hasattr(obj_, "__dict__"):
-                return _convert_object_to_dict(obj_.__dict__)
+                # This is an object - let's try to convert it to a dictionary
+                # A  naive approach would be to use the '__dict__' object directly, but that only lists the attributes
+                # In order to also serialize the properties, we use the __dir__() method
+                # Filtering by everything that is not a method gives us both attributes and properties
+                # We also (still) skip private attributes/properties, so everything that starts with an underscore
+                return {
+                    k: _convert_object_to_dict(getattr(obj_, k))
+                    for k in obj_.__dir__()
+                    if not k.startswith("_") and type(getattr(obj_, k, "")).__name__ != "method"
+                }
             return obj_
 
         return self.match(key, _convert_object_to_dict(obj))

tests/test_snapshots.py

@@ -1,4 +1,5 @@
 import io
+from enum import Enum
 
 import pytest
 
@@ -75,6 +76,67 @@ def __init__(self, name):
         sm.match_object("key_a", CustomObject(name="myname"))
         sm._assert_all()
 
+    def test_match_object_lists_and_iterators(self):
+        class CustomObject:
+            def __init__(self, name):
+                self.name = name
+                self.my_list = [9, 8, 7, 6, 5]
+                self.my_iterator = (x for x in range(5))
+
+        sm = SnapshotSession(scope_key="A", verify=True, base_file_path="", update=False)
+        sm.recorded_state = {
+            "key_a": {"name": "myname", "my_iterator": [0, 1, 2, 3, 4], "my_list": [9, 8, 7, 6, 5]}
+        }
+        sm.match_object("key_a", CustomObject(name="myname"))
+        sm._assert_all()
+
+    def test_match_object_include_properties(self):
+        class CustomObject:
+            def __init__(self, name):
+                self.name = name
+                self._internal = "n/a"
+
+            def some_method(self):
+                # method should not be serialized
+                return False
+
+            @property
+            def some_prop(self):
+                # properties should be serialized
+                return True
+
+            @property
+            def some_iterator(self):
+                for i in range(3):
+                    yield i
+
+            @property
+            def _private_prop(self):
+                # private properties should be ignored
+                return False
+
+        sm = SnapshotSession(scope_key="A", verify=True, base_file_path="", update=False)
+        sm.recorded_state = {
+            "key_a": {"name": "myname", "some_prop": True, "some_iterator": [0, 1, 2]}
+        }
+        sm.match_object("key_a", CustomObject(name="myname"))
+        sm._assert_all()
+
+    def test_match_object_enums(self):
+        class TestEnum(Enum):
+            value1 = "Value 1"
+            value2 = "Value 2"
+
+        class CustomObject:
+            def __init__(self, name):
+                self.name = name
+                self.my_enum = TestEnum.value2
+
+        sm = SnapshotSession(scope_key="A", verify=True, base_file_path="", update=False)
+        sm.recorded_state = {"key_a": {"name": "myname", "my_enum": "Value 2"}}
+        sm.match_object("key_a", CustomObject(name="myname"))
+        sm._assert_all()
+
     def test_match_object_change(self):
         class CustomObject:
             def __init__(self, name):