Don't do constructor injection on dataclasses.

src/dependency_injection/container.py

@@ -1,4 +1,5 @@
 import inspect
+from dataclasses import is_dataclass
 
 from typing import Any, Callable, Dict, List, Optional, TypeVar, Type
 
@@ -176,6 +177,9 @@ def _inject_dependencies(
         scope_name: str = None,
         constructor_args: Optional[Dict[str, Any]] = None,
     ) -> Type:
+        if is_dataclass(implementation):
+            return implementation()  # Do not inject into dataclasses
+
         constructor = inspect.signature(implementation.__init__)
         params = constructor.parameters
 

tests/unit_test/container/resolve/test_resolve_with_injection.py

@@ -1,3 +1,5 @@
+from dataclasses import dataclass
+
 from dependency_injection.container import DependencyContainer
 from unit_test.unit_test_case import UnitTestCase
 
@@ -25,3 +27,25 @@ def __init__(self, engine: Engine):
         self.assertIsInstance(resolved_dependency, Car)
         self.assertIsNotNone(resolved_dependency.engine)
         self.assertIsInstance(resolved_dependency.engine, Engine)
+
+    def test_resolve_skips_constructor_injection_for_dataclass(self):
+        # arrange
+        class Engine:
+            pass
+
+        @dataclass
+        class Car:
+            engine: Engine = None
+
+        dependency_container = DependencyContainer.get_instance()
+        dependency_container.register_transient(Engine)
+        dependency_container.register_transient(Car)
+
+        # act
+        resolved_dependency = dependency_container.resolve(Car)
+
+        # assert
+        self.assertIsInstance(resolved_dependency, Car)
+        self.assertIsNone(
+            resolved_dependency.engine
+        )  # Should be None since injection is skipped