Improve debugability of deepcopy errors

src/dependency_injector/errors.py

@@ -10,3 +10,24 @@ class Error(Exception):
 
 class NoSuchProviderError(Error, AttributeError):
     """Error that is raised when provider lookup is failed."""
+
+
+class NonCopyableArgumentError(Error):
+    """Error that is raised when provider argument is not deep-copyable."""
+
+    index: int
+    keyword: str
+    provider: object
+
+    def __init__(self, provider: object, index: int = -1, keyword: str = "") -> None:
+        self.provider = provider
+        self.index = index
+        self.keyword = keyword
+
+    def __str__(self) -> str:
+        s = (
+            f"keyword argument {self.keyword}"
+            if self.keyword
+            else f"argument at index {self.index}"
+        )
+        return f"Couldn't copy {s} for provider {self.provider!r}"

src/dependency_injector/providers.pyi

@@ -530,7 +530,21 @@ def is_delegated(instance: Any) -> bool: ...
 def represent_provider(provider: Provider, provides: Any) -> str: ...
 
 
-def deepcopy(instance: Any, memo: Optional[_Dict[Any, Any]] = None): Any: ...
+def deepcopy(instance: Any, memo: Optional[_Dict[Any, Any]] = None) -> Any: ...
+
+
+def deepcopy_args(
+    provider: Provider[Any],
+    args: Tuple[Any, ...],
+    memo: Optional[_Dict[int, Any]] = None,
+) -> Tuple[Any, ...]: ...
+
+
+def deepcopy_kwargs(
+    provider: Provider[Any],
+    kwargs: _Dict[str, Any],
+    memo: Optional[_Dict[int, Any]] = None,
+) -> Dict[str, Any]: ...
 
 
 def merge_dicts(dict1: _Dict[Any, Any], dict2: _Dict[Any, Any]) -> _Dict[Any, Any]: ...

src/dependency_injector/providers.pyx

@@ -71,6 +71,7 @@ except ImportError:
 from .errors import (
     Error,
     NoSuchProviderError,
+    NonCopyableArgumentError,
 )
 
 cimport cython
@@ -1252,8 +1253,8 @@ cdef class Callable(Provider):
 
         copied = _memorized_duplicate(self, memo)
         copied.set_provides(_copy_if_provider(self.provides, memo))
-        copied.set_args(*deepcopy(self.args, memo))
-        copied.set_kwargs(**deepcopy(self.kwargs, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
+        copied.set_kwargs(**deepcopy_kwargs(self, self.kwargs, memo))
         self._copy_overridings(copied, memo)
         return copied
 
@@ -2539,8 +2540,8 @@ cdef class Factory(Provider):
 
         copied = _memorized_duplicate(self, memo)
         copied.set_provides(_copy_if_provider(self.provides, memo))
-        copied.set_args(*deepcopy(self.args, memo))
-        copied.set_kwargs(**deepcopy(self.kwargs, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
+        copied.set_kwargs(**deepcopy_kwargs(self, self.kwargs, memo))
         copied.set_attributes(**deepcopy(self.attributes, memo))
         self._copy_overridings(copied, memo)
         return copied
@@ -2838,8 +2839,8 @@ cdef class BaseSingleton(Provider):
 
         copied = _memorized_duplicate(self, memo)
         copied.set_provides(_copy_if_provider(self.provides, memo))
-        copied.set_args(*deepcopy(self.args, memo))
-        copied.set_kwargs(**deepcopy(self.kwargs, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
+        copied.set_kwargs(**deepcopy_kwargs(self, self.kwargs, memo))
         copied.set_attributes(**deepcopy(self.attributes, memo))
         self._copy_overridings(copied, memo)
         return copied
@@ -3451,7 +3452,7 @@ cdef class List(Provider):
             return copied
 
         copied = _memorized_duplicate(self, memo)
-        copied.set_args(*deepcopy(self.args, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
         self._copy_overridings(copied, memo)
         return copied
 
@@ -3674,8 +3675,8 @@ cdef class Resource(Provider):
 
         copied = _memorized_duplicate(self, memo)
         copied.set_provides(_copy_if_provider(self.provides, memo))
-        copied.set_args(*deepcopy(self.args, memo))
-        copied.set_kwargs(**deepcopy(self.kwargs, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
+        copied.set_kwargs(**deepcopy_kwargs(self, self.kwargs, memo))
 
         self._copy_overridings(copied, memo)
 
@@ -4525,8 +4526,8 @@ cdef class MethodCaller(Provider):
 
         copied = _memorized_duplicate(self, memo)
         copied.set_provides(_copy_if_provider(self.provides, memo))
-        copied.set_args(*deepcopy(self.args, memo))
-        copied.set_kwargs(**deepcopy(self.kwargs, memo))
+        copied.set_args(*deepcopy_args(self, self.args, memo))
+        copied.set_kwargs(**deepcopy_kwargs(self, self.kwargs, memo))
         self._copy_overridings(copied, memo)
         return copied
 
@@ -4927,6 +4928,48 @@ cpdef object deepcopy(object instance, dict memo=None):
     return copy.deepcopy(instance, memo)
 
 
+cpdef tuple deepcopy_args(
+    Provider provider,
+    tuple args,
+    dict[int, object] memo = None,
+):
+    """A wrapper for deepcopy for positional arguments.
+
+    Used to improve debugability of objects that cannot be deep-copied.
+    """
+
+    cdef list[object] out = []
+
+    for i, arg in enumerate(args):
+        try:
+            out.append(copy.deepcopy(arg, memo))
+        except Exception as e:
+            raise NonCopyableArgumentError(provider, index=i) from e
+
+    return tuple(out)
+
+
+cpdef dict[str, object] deepcopy_kwargs(
+    Provider provider,
+    dict[str, object] kwargs,
+    dict[int, object] memo = None,
+):
+    """A wrapper for deepcopy for keyword arguments.
+
+    Used to improve debugability of objects that cannot be deep-copied.
+    """
+
+    cdef dict[str, object] out = {}
+
+    for name, arg in kwargs.items():
+        try:
+            out[name] = copy.deepcopy(arg, memo)
+        except Exception as e:
+            raise NonCopyableArgumentError(provider, keyword=name) from e
+
+    return out
+
+
 def __add_sys_streams(memo):
     """Add system streams to memo dictionary.
 

tests/unit/providers/utils/test_deepcopy_py3.py

@@ -0,0 +1,65 @@
+import sys
+from typing import Any, Dict, NoReturn
+
+from pytest import raises
+
+from dependency_injector.errors import NonCopyableArgumentError
+from dependency_injector.providers import (
+    Provider,
+    deepcopy,
+    deepcopy_args,
+    deepcopy_kwargs,
+)
+
+
+class NonCopiable:
+    def __deepcopy__(self, memo: Dict[int, Any]) -> NoReturn:
+        raise NotImplementedError
+
+
+def test_deepcopy_streams_not_copied() -> None:
+    l = [sys.stdin, sys.stdout, sys.stderr]
+    assert deepcopy(l) == l
+
+
+def test_deepcopy_args() -> None:
+    provider = Provider[None]()
+    copiable = NonCopiable()
+    memo: Dict[int, Any] = {id(copiable): copiable}
+
+    assert deepcopy_args(provider, (1, copiable), memo) == (1, copiable)
+
+
+def test_deepcopy_args_non_copiable() -> None:
+    provider = Provider[None]()
+    copiable = NonCopiable()
+    memo: Dict[int, Any] = {id(copiable): copiable}
+
+    with raises(
+        NonCopyableArgumentError,
+        match=r"^Couldn't copy argument at index 3 for provider ",
+    ):
+        deepcopy_args(provider, (1, copiable, object(), NonCopiable()), memo)
+
+
+def test_deepcopy_kwargs() -> None:
+    provider = Provider[None]()
+    copiable = NonCopiable()
+    memo: Dict[int, Any] = {id(copiable): copiable}
+
+    assert deepcopy_kwargs(provider, {"x": 1, "y": copiable}, memo) == {
+        "x": 1,
+        "y": copiable,
+    }
+
+
+def test_deepcopy_kwargs_non_copiable() -> None:
+    provider = Provider[None]()
+    copiable = NonCopiable()
+    memo: Dict[int, Any] = {id(copiable): copiable}
+
+    with raises(
+        NonCopyableArgumentError,
+        match=r"^Couldn't copy keyword argument z for provider ",
+    ):
+        deepcopy_kwargs(provider, {"x": 1, "y": copiable, "z": NonCopiable()}, memo)