Make attrgetter extract value from any nesting level of objects (#57)

* Fix attrgetter logic to get the attribute value at any nesting level of objects

---------

Co-authored-by: ivan <ivan.belyaev@ailet.com>

Author: nightblure

tests/test_attr_getter.py

@@ -0,0 +1,66 @@
+import random
+from dataclasses import dataclass, field
+
+import pytest
+
+from that_depends import providers
+from that_depends.providers.attr_getter import _get_value_from_object_by_dotted_path
+
+
+@dataclass
+class Nested2:
+    some_const = 144
+
+
+@dataclass
+class Nested1:
+    nested2_attr: Nested2 = field(default_factory=Nested2)
+
+
+@dataclass
+class Settings:
+    some_str_value: str = "some_string_value"
+    some_int_value: int = 3453621
+    nested1_attr: Nested1 = field(default_factory=Nested1)
+
+
+@dataclass
+class NestingTestDTO: ...
+
+
+@pytest.fixture()
+def some_settings_provider() -> providers.Singleton[Settings]:
+    return providers.Singleton(Settings)
+
+
+def test_attr_getter_with_zero_attribute_depth(some_settings_provider: providers.Singleton[Settings]) -> None:
+    attr_getter = some_settings_provider.some_str_value
+    assert attr_getter.sync_resolve() == Settings().some_str_value
+
+
+def test_attr_getter_with_more_than_zero_attribute_depth(some_settings_provider: providers.Singleton[Settings]) -> None:
+    attr_getter = some_settings_provider.nested1_attr.nested2_attr.some_const
+    assert attr_getter.sync_resolve() == Nested2().some_const
+
+
+@pytest.mark.parametrize(
+    ("field_count", "test_field_name", "test_value"),
+    [(1, "test_field", "sdf6fF^SF(FF*4ffsf"), (5, "nested_field", -252625), (50, "50_lvl_field", 909234235)],
+)
+def test_nesting_levels(field_count: int, test_field_name: str, test_value: str | int) -> None:
+    obj = NestingTestDTO()
+    fields = [f"field_{i}" for i in range(1, field_count + 1)]
+    random.shuffle(fields)
+
+    attr_path = ".".join(fields) + f".{test_field_name}"
+    obj_copy = obj
+
+    while fields:
+        field_name = fields.pop(0)
+        setattr(obj_copy, field_name, NestingTestDTO())
+        obj_copy = obj_copy.__getattribute__(field_name)
+
+    setattr(obj_copy, test_field_name, test_value)
+
+    attr_value = _get_value_from_object_by_dotted_path(obj, attr_path)
+    assert attr_value == test_value

that_depends/providers/attr_getter.py

@@ -1,4 +1,5 @@
 import typing
+from operator import attrgetter
 
 from that_depends.providers.base import AbstractProvider
 
@@ -7,15 +8,28 @@
 P = typing.ParamSpec("P")
 
 
+def _get_value_from_object_by_dotted_path(obj: typing.Any, path: str) -> typing.Any:  # noqa: ANN401
+    attribute_getter = attrgetter(path)
+    return attribute_getter(obj)
+
+
 class AttrGetter(AbstractProvider[T]):
-    __slots__ = "_provider", "_attr_name"
+    __slots__ = "_provider", "_attrs"
 
     def __init__(self, provider: AbstractProvider[T], attr_name: str) -> None:
         self._provider = provider
-        self._attr_name = attr_name
+        self._attrs = [attr_name]
+
+    def __getattr__(self, attr: str) -> "AttrGetter[T]":
+        self._attrs.append(attr)
+        return self
 
     async def async_resolve(self) -> typing.Any:  # noqa: ANN401
-        return getattr(await self._provider.async_resolve(), self._attr_name)
+        resolved_provider_object = await self._provider.async_resolve()
+        attribute_path = ".".join(self._attrs)
+        return _get_value_from_object_by_dotted_path(resolved_provider_object, attribute_path)
 
     def sync_resolve(self) -> typing.Any:  # noqa: ANN401
-        return getattr(self._provider.sync_resolve(), self._attr_name)
+        resolved_provider_object = self._provider.sync_resolve()
+        attribute_path = ".".join(self._attrs)
+        return _get_value_from_object_by_dotted_path(resolved_provider_object, attribute_path)