Feature: Context local provider (#442)

Co-authored-by: Rollo Konig Brock <rollo@b2c2.com>

src/dependency_injector/providers.pxd

@@ -175,6 +175,11 @@ cdef class ThreadLocalSingleton(BaseSingleton):
     cpdef object _provide(self, tuple args, dict kwargs)
 
 
+cdef class ContextLocalSingleton(BaseSingleton):
+
+    cpdef object _provide(self, tuple args, dict kwargs)
+
+
 cdef class DelegatedThreadLocalSingleton(ThreadLocalSingleton):
     pass
 

src/dependency_injector/providers.pyi

@@ -336,6 +336,9 @@ class DelegatedThreadSafeSingleton(ThreadSafeSingleton[T]): ...
 class ThreadLocalSingleton(BaseSingleton[T]): ...
 
 
+class ContextLocalSingleton(BaseSingleton[T]): ...
+
+
 class DelegatedThreadLocalSingleton(ThreadLocalSingleton[T]): ...
 
 

src/dependency_injector/providers.pyx

@@ -13,6 +13,12 @@ import types
 import threading
 import warnings
 
+try:
+    import contextvars
+except ImportError:
+    contextvars = None
+
+
 try:
     import asyncio
 except ImportError:
@@ -2928,6 +2934,89 @@ cdef class ThreadLocalSingleton(BaseSingleton):
             future_result.set_result(instance)
 
 
+cdef class ContextLocalSingleton(BaseSingleton):
+    """Context-local singleton provides single objects in scope of a context.
+
+    .. py:attribute:: provided_type
+
+        If provided type is defined, provider checks that providing class is
+        its subclass.
+
+        :type: type | None
+
+    .. py:attribute:: cls
+       :noindex:
+
+        Class that provides object.
+        Alias for :py:attr:`provides`.
+
+        :type: type
+    """
+    _none = object()
+
+    def __init__(self, provides=None, *args, **kwargs):
+        """Initializer.
+
+        :param provides: Provided type.
+        :type provides: type
+        """
+        if not contextvars:
+            raise RuntimeError(
+                'Contextvars library not found. This provider '
+                'requires Python 3.7 or a backport of contextvars. '
+                'To install a backport run "pip install contextvars".'
+            )
+
+        super(ContextLocalSingleton, self).__init__(provides, *args, **kwargs)
+        self.__storage = contextvars.ContextVar('__storage', default=self._none)
+
+    def reset(self):
+        """Reset cached instance, if any.
+
+        :rtype: None
+        """
+        instance = self.__storage.get()
+        if instance is self._none:
+            return SingletonResetContext(self)
+
+        if __is_future_or_coroutine(instance):
+            asyncio.ensure_future(instance).cancel()
+
+        self.__storage.set(self._none)
+
+        return SingletonResetContext(self)
+
+    cpdef object _provide(self, tuple args, dict kwargs):
+        """Return single instance."""
+        cdef object instance
+
+        instance = self.__storage.get()
+
+        if instance is self._none:
+            instance = __factory_call(self.__instantiator, args, kwargs)
+
+            if __is_future_or_coroutine(instance):
+                future_result = asyncio.Future()
+                instance = asyncio.ensure_future(instance)
+                instance.add_done_callback(functools.partial(self._async_init_instance, future_result))
+                self.__storage.set(future_result)
+                return future_result
+
+            self.__storage.set(instance)
+
+        return instance
+
+    def _async_init_instance(self, future_result, result):
+        try:
+            instance = result.result()
+        except Exception as exception:
+            self.__storage.set(self._none)
+            future_result.set_exception(exception)
+        else:
+            self.__storage.set(instance)
+            future_result.set_result(instance)
+
+
 cdef class DelegatedThreadLocalSingleton(ThreadLocalSingleton):
     """Delegated thread-local singleton is injected "as is".
 

tests/unit/providers/singleton_common.py

@@ -0,0 +1,434 @@
+import sys
+
+from dependency_injector import providers, errors
+
+
+class Example(object):
+
+    def __init__(self, init_arg1=None, init_arg2=None, init_arg3=None,
+                 init_arg4=None):
+        self.init_arg1 = init_arg1
+        self.init_arg2 = init_arg2
+        self.init_arg3 = init_arg3
+        self.init_arg4 = init_arg4
+
+        self.attribute1 = None
+        self.attribute2 = None
+
+
+class _BaseSingletonTestCase(object):
+
+    singleton_cls = None
+
+    def test_is_provider(self):
+        self.assertTrue(providers.is_provider(self.singleton_cls(Example)))
+
+    def test_init_with_callable(self):
+        self.assertTrue(self.singleton_cls(credits))
+
+    def test_init_with_not_callable(self):
+        self.assertRaises(errors.Error, self.singleton_cls, 123)
+
+    def test_init_optional_provides(self):
+        provider = self.singleton_cls()
+        provider.set_provides(object)
+        self.assertIs(provider.provides, object)
+        self.assertIsInstance(provider(), object)
+
+    def test_set_provides_returns_self(self):
+        provider = self.singleton_cls()
+        self.assertIs(provider.set_provides(object), provider)
+
+    def test_init_with_valid_provided_type(self):
+        class ExampleProvider(self.singleton_cls):
+            provided_type = Example
+
+        example_provider = ExampleProvider(Example, 1, 2)
+
+        self.assertIsInstance(example_provider(), Example)
+
+    def test_init_with_valid_provided_subtype(self):
+        class ExampleProvider(self.singleton_cls):
+            provided_type = Example
+
+        class NewExampe(Example):
+            pass
+
+        example_provider = ExampleProvider(NewExampe, 1, 2)
+
+        self.assertIsInstance(example_provider(), NewExampe)
+
+    def test_init_with_invalid_provided_type(self):
+        class ExampleProvider(self.singleton_cls):
+            provided_type = Example
+
+        with self.assertRaises(errors.Error):
+            ExampleProvider(list)
+
+    def test_provided_instance_provider(self):
+        provider = providers.Singleton(Example)
+        self.assertIsInstance(provider.provided, providers.ProvidedInstance)
+
+    def test_call(self):
+        provider = self.singleton_cls(Example)
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_args(self):
+        provider = self.singleton_cls(Example, 'i1', 'i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_keyword_args(self):
+        provider = self.singleton_cls(Example, init_arg1='i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_init_positional_and_keyword_args(self):
+        provider = self.singleton_cls(Example, 'i1', init_arg2='i2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.init_arg1, 'i1')
+        self.assertEqual(instance1.init_arg2, 'i2')
+
+        self.assertEqual(instance2.init_arg1, 'i1')
+        self.assertEqual(instance2.init_arg2, 'i2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_attributes(self):
+        provider = self.singleton_cls(Example)
+        provider.add_attributes(attribute1='a1', attribute2='a2')
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertEqual(instance1.attribute1, 'a1')
+        self.assertEqual(instance1.attribute2, 'a2')
+
+        self.assertEqual(instance2.attribute1, 'a1')
+        self.assertEqual(instance2.attribute2, 'a2')
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, Example)
+        self.assertIsInstance(instance2, Example)
+
+    def test_call_with_context_args(self):
+        provider = self.singleton_cls(Example)
+
+        instance = provider(11, 22)
+
+        self.assertEqual(instance.init_arg1, 11)
+        self.assertEqual(instance.init_arg2, 22)
+
+    def test_call_with_context_kwargs(self):
+        provider = self.singleton_cls(Example, init_arg1=1)
+
+        instance1 = provider(init_arg2=22)
+        self.assertEqual(instance1.init_arg1, 1)
+        self.assertEqual(instance1.init_arg2, 22)
+
+        # Instance is created earlier
+        instance1 = provider(init_arg1=11, init_arg2=22)
+        self.assertEqual(instance1.init_arg1, 1)
+        self.assertEqual(instance1.init_arg2, 22)
+
+    def test_call_with_context_args_and_kwargs(self):
+        provider = self.singleton_cls(Example, 11)
+
+        instance = provider(22, init_arg3=33, init_arg4=44)
+
+        self.assertEqual(instance.init_arg1, 11)
+        self.assertEqual(instance.init_arg2, 22)
+        self.assertEqual(instance.init_arg3, 33)
+        self.assertEqual(instance.init_arg4, 44)
+
+    def test_fluent_interface(self):
+        provider = self.singleton_cls(Example) \
+            .add_args(1, 2) \
+            .add_kwargs(init_arg3=3, init_arg4=4) \
+            .add_attributes(attribute1=5, attribute2=6)
+
+        instance = provider()
+
+        self.assertEqual(instance.init_arg1, 1)
+        self.assertEqual(instance.init_arg2, 2)
+        self.assertEqual(instance.init_arg3, 3)
+        self.assertEqual(instance.init_arg4, 4)
+        self.assertEqual(instance.attribute1, 5)
+        self.assertEqual(instance.attribute2, 6)
+
+    def test_set_args(self):
+        provider = self.singleton_cls(Example) \
+            .add_args(1, 2) \
+            .set_args(3, 4)
+        self.assertEqual(provider.args, (3, 4))
+
+    def test_set_kwargs(self):
+        provider = self.singleton_cls(Example) \
+            .add_kwargs(init_arg3=3, init_arg4=4) \
+            .set_kwargs(init_arg3=4, init_arg4=5)
+        self.assertEqual(provider.kwargs, dict(init_arg3=4, init_arg4=5))
+
+    def test_set_attributes(self):
+        provider = self.singleton_cls(Example) \
+            .add_attributes(attribute1=5, attribute2=6) \
+            .set_attributes(attribute1=6, attribute2=7)
+        self.assertEqual(provider.attributes, dict(attribute1=6, attribute2=7))
+
+    def test_clear_args(self):
+        provider = self.singleton_cls(Example) \
+            .add_args(1, 2) \
+            .clear_args()
+        self.assertEqual(provider.args, tuple())
+
+    def test_clear_kwargs(self):
+        provider = self.singleton_cls(Example) \
+            .add_kwargs(init_arg3=3, init_arg4=4) \
+            .clear_kwargs()
+        self.assertEqual(provider.kwargs, dict())
+
+    def test_clear_attributes(self):
+        provider = self.singleton_cls(Example) \
+            .add_attributes(attribute1=5, attribute2=6) \
+            .clear_attributes()
+        self.assertEqual(provider.attributes, dict())
+
+    def test_call_overridden(self):
+        provider = self.singleton_cls(Example)
+        overriding_provider1 = self.singleton_cls(dict)
+        overriding_provider2 = self.singleton_cls(list)
+
+        provider.override(overriding_provider1)
+        provider.override(overriding_provider2)
+
+        instance1 = provider()
+        instance2 = provider()
+
+        self.assertIs(instance1, instance2)
+        self.assertIsInstance(instance1, list)
+        self.assertIsInstance(instance2, list)
+
+    def test_deepcopy(self):
+        provider = self.singleton_cls(Example)
+
+        provider_copy = providers.deepcopy(provider)
+
+        self.assertIsNot(provider, provider_copy)
+        self.assertIs(provider.cls, provider_copy.cls)
+        self.assertIsInstance(provider, self.singleton_cls)
+
+    def test_deepcopy_from_memo(self):
+        provider = self.singleton_cls(Example)
+        provider_copy_memo = self.singleton_cls(Example)
+
+        provider_copy = providers.deepcopy(
+            provider, memo={id(provider): provider_copy_memo})
+
+        self.assertIs(provider_copy, provider_copy_memo)
+
+    def test_deepcopy_args(self):
+        provider = self.singleton_cls(Example)
+        dependent_provider1 = self.singleton_cls(list)
+        dependent_provider2 = self.singleton_cls(dict)
+
+        provider.add_args(dependent_provider1, dependent_provider2)
+
+        provider_copy = providers.deepcopy(provider)
+        dependent_provider_copy1 = provider_copy.args[0]
+        dependent_provider_copy2 = provider_copy.args[1]
+
+        self.assertNotEqual(provider.args, provider_copy.args)
+
+        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
+        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
+
+        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
+        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
+
+    def test_deepcopy_kwargs(self):
+        provider = self.singleton_cls(Example)
+        dependent_provider1 = self.singleton_cls(list)
+        dependent_provider2 = self.singleton_cls(dict)
+
+        provider.add_kwargs(a1=dependent_provider1, a2=dependent_provider2)
+
+        provider_copy = providers.deepcopy(provider)
+        dependent_provider_copy1 = provider_copy.kwargs['a1']
+        dependent_provider_copy2 = provider_copy.kwargs['a2']
+
+        self.assertNotEqual(provider.kwargs, provider_copy.kwargs)
+
+        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
+        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
+
+        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
+        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
+
+    def test_deepcopy_attributes(self):
+        provider = self.singleton_cls(Example)
+        dependent_provider1 = self.singleton_cls(list)
+        dependent_provider2 = self.singleton_cls(dict)
+
+        provider.add_attributes(a1=dependent_provider1, a2=dependent_provider2)
+
+        provider_copy = providers.deepcopy(provider)
+        dependent_provider_copy1 = provider_copy.attributes['a1']
+        dependent_provider_copy2 = provider_copy.attributes['a2']
+
+        self.assertNotEqual(provider.attributes, provider_copy.attributes)
+
+        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
+        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
+
+        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
+        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
+
+    def test_deepcopy_overridden(self):
+        provider = self.singleton_cls(Example)
+        object_provider = providers.Object(object())
+
+        provider.override(object_provider)
+
+        provider_copy = providers.deepcopy(provider)
+        object_provider_copy = provider_copy.overridden[0]
+
+        self.assertIsNot(provider, provider_copy)
+        self.assertIs(provider.cls, provider_copy.cls)
+        self.assertIsInstance(provider, self.singleton_cls)
+
+        self.assertIsNot(object_provider, object_provider_copy)
+        self.assertIsInstance(object_provider_copy, providers.Object)
+
+    def test_deepcopy_with_sys_streams(self):
+        provider = providers.Singleton(Example)
+        provider.add_args(sys.stdin)
+        provider.add_kwargs(a2=sys.stdout)
+        provider.add_attributes(a3=sys.stderr)
+
+        provider_copy = providers.deepcopy(provider)
+
+        self.assertIsNot(provider, provider_copy)
+        self.assertIsInstance(provider_copy, providers.Singleton)
+        self.assertIs(provider.args[0], sys.stdin)
+        self.assertIs(provider.kwargs['a2'], sys.stdout)
+        self.assertIs(provider.attributes['a3'], sys.stderr)
+
+    def test_reset(self):
+        provider = self.singleton_cls(object)
+
+        instance1 = provider()
+        self.assertIsInstance(instance1, object)
+
+        provider.reset()
+
+        instance2 = provider()
+        self.assertIsInstance(instance2, object)
+
+        self.assertIsNot(instance1, instance2)
+
+    def test_reset_with_singleton(self):
+        dependent_singleton = providers.Singleton(object)
+        provider = self.singleton_cls(dict, dependency=dependent_singleton)
+
+        dependent_instance = dependent_singleton()
+        instance1 = provider()
+        self.assertIs(instance1['dependency'], dependent_instance)
+
+        provider.reset()
+
+        instance2 = provider()
+        self.assertIs(instance1['dependency'], dependent_instance)
+
+        self.assertIsNot(instance1, instance2)
+
+    def test_reset_context_manager(self):
+        singleton = self.singleton_cls(object)
+
+        instance1 = singleton()
+        with singleton.reset():
+            instance2 = singleton()
+        instance3 = singleton()
+        self.assertEqual(len({instance1, instance2, instance3}), 3)
+
+    def test_reset_context_manager_as_attribute(self):
+        singleton = self.singleton_cls(object)
+
+        with singleton.reset() as alias:
+            pass
+
+        self.assertIs(singleton, alias)
+
+    def test_full_reset(self):
+        dependent_singleton = providers.Singleton(object)
+        provider = self.singleton_cls(dict, dependency=dependent_singleton)
+
+        dependent_instance1 = dependent_singleton()
+        instance1 = provider()
+        self.assertIs(instance1['dependency'], dependent_instance1)
+
+        provider.full_reset()
+
+        dependent_instance2 = dependent_singleton()
+        instance2 = provider()
+        self.assertIsNot(instance2['dependency'], dependent_instance1)
+        self.assertIsNot(dependent_instance1, dependent_instance2)
+        self.assertIsNot(instance1, instance2)
+
+    def test_full_reset_context_manager(self):
+        class Item:
+            def __init__(self, dependency):
+                self.dependency = dependency
+
+        dependent_singleton = providers.Singleton(object)
+        singleton = self.singleton_cls(Item, dependency=dependent_singleton)
+
+        instance1 = singleton()
+        with singleton.full_reset():
+            instance2 = singleton()
+        instance3 = singleton()
+
+        self.assertEqual(len({instance1, instance2, instance3}), 3)
+        self.assertEqual(
+            len({instance1.dependency, instance2.dependency, instance3.dependency}),
+            3,
+        )
+
+    def test_full_reset_context_manager_as_attribute(self):
+        singleton = self.singleton_cls(object)
+
+        with singleton.full_reset() as alias:
+            pass
+
+        self.assertIs(singleton, alias)

tests/unit/providers/test_singletons_py2_py3.py

@@ -1,7 +1,5 @@
 """Dependency injector singleton providers unit tests."""
 
-import sys
-
 import unittest
 
 from dependency_injector import (
@@ -9,436 +7,7 @@ from dependency_injector import (
     errors,
 )
 
-
+from .singleton_common import Example, _BaseSingletonTestCase
-class Example(object):
-
-    def __init__(self, init_arg1=None, init_arg2=None, init_arg3=None,
-                 init_arg4=None):
-        self.init_arg1 = init_arg1
-        self.init_arg2 = init_arg2
-        self.init_arg3 = init_arg3
-        self.init_arg4 = init_arg4
-
-        self.attribute1 = None
-        self.attribute2 = None
-
-
-class _BaseSingletonTestCase(object):
-
-    singleton_cls = None
-
-    def test_is_provider(self):
-        self.assertTrue(providers.is_provider(self.singleton_cls(Example)))
-
-    def test_init_with_callable(self):
-        self.assertTrue(self.singleton_cls(credits))
-
-    def test_init_with_not_callable(self):
-        self.assertRaises(errors.Error, self.singleton_cls, 123)
-
-    def test_init_optional_provides(self):
-        provider = self.singleton_cls()
-        provider.set_provides(object)
-        self.assertIs(provider.provides, object)
-        self.assertIsInstance(provider(), object)
-
-    def test_set_provides_returns_self(self):
-        provider = self.singleton_cls()
-        self.assertIs(provider.set_provides(object), provider)
-
-    def test_init_with_valid_provided_type(self):
-        class ExampleProvider(self.singleton_cls):
-            provided_type = Example
-
-        example_provider = ExampleProvider(Example, 1, 2)
-
-        self.assertIsInstance(example_provider(), Example)
-
-    def test_init_with_valid_provided_subtype(self):
-        class ExampleProvider(self.singleton_cls):
-            provided_type = Example
-
-        class NewExampe(Example):
-            pass
-
-        example_provider = ExampleProvider(NewExampe, 1, 2)
-
-        self.assertIsInstance(example_provider(), NewExampe)
-
-    def test_init_with_invalid_provided_type(self):
-        class ExampleProvider(self.singleton_cls):
-            provided_type = Example
-
-        with self.assertRaises(errors.Error):
-            ExampleProvider(list)
-
-    def test_provided_instance_provider(self):
-        provider = providers.Singleton(Example)
-        self.assertIsInstance(provider.provided, providers.ProvidedInstance)
-
-    def test_call(self):
-        provider = self.singleton_cls(Example)
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, Example)
-
-    def test_call_with_init_positional_args(self):
-        provider = self.singleton_cls(Example, 'i1', 'i2')
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertEqual(instance1.init_arg1, 'i1')
-        self.assertEqual(instance1.init_arg2, 'i2')
-
-        self.assertEqual(instance2.init_arg1, 'i1')
-        self.assertEqual(instance2.init_arg2, 'i2')
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, Example)
-
-    def test_call_with_init_keyword_args(self):
-        provider = self.singleton_cls(Example, init_arg1='i1', init_arg2='i2')
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertEqual(instance1.init_arg1, 'i1')
-        self.assertEqual(instance1.init_arg2, 'i2')
-
-        self.assertEqual(instance2.init_arg1, 'i1')
-        self.assertEqual(instance2.init_arg2, 'i2')
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, Example)
-
-    def test_call_with_init_positional_and_keyword_args(self):
-        provider = self.singleton_cls(Example, 'i1', init_arg2='i2')
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertEqual(instance1.init_arg1, 'i1')
-        self.assertEqual(instance1.init_arg2, 'i2')
-
-        self.assertEqual(instance2.init_arg1, 'i1')
-        self.assertEqual(instance2.init_arg2, 'i2')
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, Example)
-
-    def test_call_with_attributes(self):
-        provider = self.singleton_cls(Example)
-        provider.add_attributes(attribute1='a1', attribute2='a2')
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertEqual(instance1.attribute1, 'a1')
-        self.assertEqual(instance1.attribute2, 'a2')
-
-        self.assertEqual(instance2.attribute1, 'a1')
-        self.assertEqual(instance2.attribute2, 'a2')
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, Example)
-        self.assertIsInstance(instance2, Example)
-
-    def test_call_with_context_args(self):
-        provider = self.singleton_cls(Example)
-
-        instance = provider(11, 22)
-
-        self.assertEqual(instance.init_arg1, 11)
-        self.assertEqual(instance.init_arg2, 22)
-
-    def test_call_with_context_kwargs(self):
-        provider = self.singleton_cls(Example, init_arg1=1)
-
-        instance1 = provider(init_arg2=22)
-        self.assertEqual(instance1.init_arg1, 1)
-        self.assertEqual(instance1.init_arg2, 22)
-
-        # Instance is created earlier
-        instance1 = provider(init_arg1=11, init_arg2=22)
-        self.assertEqual(instance1.init_arg1, 1)
-        self.assertEqual(instance1.init_arg2, 22)
-
-    def test_call_with_context_args_and_kwargs(self):
-        provider = self.singleton_cls(Example, 11)
-
-        instance = provider(22, init_arg3=33, init_arg4=44)
-
-        self.assertEqual(instance.init_arg1, 11)
-        self.assertEqual(instance.init_arg2, 22)
-        self.assertEqual(instance.init_arg3, 33)
-        self.assertEqual(instance.init_arg4, 44)
-
-    def test_fluent_interface(self):
-        provider = self.singleton_cls(Example) \
-            .add_args(1, 2) \
-            .add_kwargs(init_arg3=3, init_arg4=4) \
-            .add_attributes(attribute1=5, attribute2=6)
-
-        instance = provider()
-
-        self.assertEqual(instance.init_arg1, 1)
-        self.assertEqual(instance.init_arg2, 2)
-        self.assertEqual(instance.init_arg3, 3)
-        self.assertEqual(instance.init_arg4, 4)
-        self.assertEqual(instance.attribute1, 5)
-        self.assertEqual(instance.attribute2, 6)
-
-    def test_set_args(self):
-        provider = self.singleton_cls(Example) \
-            .add_args(1, 2) \
-            .set_args(3, 4)
-        self.assertEqual(provider.args, (3, 4))
-
-    def test_set_kwargs(self):
-        provider = self.singleton_cls(Example) \
-            .add_kwargs(init_arg3=3, init_arg4=4) \
-            .set_kwargs(init_arg3=4, init_arg4=5)
-        self.assertEqual(provider.kwargs, dict(init_arg3=4, init_arg4=5))
-
-    def test_set_attributes(self):
-        provider = self.singleton_cls(Example) \
-            .add_attributes(attribute1=5, attribute2=6) \
-            .set_attributes(attribute1=6, attribute2=7)
-        self.assertEqual(provider.attributes, dict(attribute1=6, attribute2=7))
-
-    def test_clear_args(self):
-        provider = self.singleton_cls(Example) \
-            .add_args(1, 2) \
-            .clear_args()
-        self.assertEqual(provider.args, tuple())
-
-    def test_clear_kwargs(self):
-        provider = self.singleton_cls(Example) \
-            .add_kwargs(init_arg3=3, init_arg4=4) \
-            .clear_kwargs()
-        self.assertEqual(provider.kwargs, dict())
-
-    def test_clear_attributes(self):
-        provider = self.singleton_cls(Example) \
-            .add_attributes(attribute1=5, attribute2=6) \
-            .clear_attributes()
-        self.assertEqual(provider.attributes, dict())
-
-    def test_call_overridden(self):
-        provider = self.singleton_cls(Example)
-        overriding_provider1 = self.singleton_cls(dict)
-        overriding_provider2 = self.singleton_cls(list)
-
-        provider.override(overriding_provider1)
-        provider.override(overriding_provider2)
-
-        instance1 = provider()
-        instance2 = provider()
-
-        self.assertIs(instance1, instance2)
-        self.assertIsInstance(instance1, list)
-        self.assertIsInstance(instance2, list)
-
-    def test_deepcopy(self):
-        provider = self.singleton_cls(Example)
-
-        provider_copy = providers.deepcopy(provider)
-
-        self.assertIsNot(provider, provider_copy)
-        self.assertIs(provider.cls, provider_copy.cls)
-        self.assertIsInstance(provider, self.singleton_cls)
-
-    def test_deepcopy_from_memo(self):
-        provider = self.singleton_cls(Example)
-        provider_copy_memo = self.singleton_cls(Example)
-
-        provider_copy = providers.deepcopy(
-            provider, memo={id(provider): provider_copy_memo})
-
-        self.assertIs(provider_copy, provider_copy_memo)
-
-    def test_deepcopy_args(self):
-        provider = self.singleton_cls(Example)
-        dependent_provider1 = self.singleton_cls(list)
-        dependent_provider2 = self.singleton_cls(dict)
-
-        provider.add_args(dependent_provider1, dependent_provider2)
-
-        provider_copy = providers.deepcopy(provider)
-        dependent_provider_copy1 = provider_copy.args[0]
-        dependent_provider_copy2 = provider_copy.args[1]
-
-        self.assertNotEqual(provider.args, provider_copy.args)
-
-        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
-        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
-
-        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
-        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
-
-    def test_deepcopy_kwargs(self):
-        provider = self.singleton_cls(Example)
-        dependent_provider1 = self.singleton_cls(list)
-        dependent_provider2 = self.singleton_cls(dict)
-
-        provider.add_kwargs(a1=dependent_provider1, a2=dependent_provider2)
-
-        provider_copy = providers.deepcopy(provider)
-        dependent_provider_copy1 = provider_copy.kwargs['a1']
-        dependent_provider_copy2 = provider_copy.kwargs['a2']
-
-        self.assertNotEqual(provider.kwargs, provider_copy.kwargs)
-
-        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
-        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
-
-        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
-        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
-
-    def test_deepcopy_attributes(self):
-        provider = self.singleton_cls(Example)
-        dependent_provider1 = self.singleton_cls(list)
-        dependent_provider2 = self.singleton_cls(dict)
-
-        provider.add_attributes(a1=dependent_provider1, a2=dependent_provider2)
-
-        provider_copy = providers.deepcopy(provider)
-        dependent_provider_copy1 = provider_copy.attributes['a1']
-        dependent_provider_copy2 = provider_copy.attributes['a2']
-
-        self.assertNotEqual(provider.attributes, provider_copy.attributes)
-
-        self.assertIs(dependent_provider1.cls, dependent_provider_copy1.cls)
-        self.assertIsNot(dependent_provider1, dependent_provider_copy1)
-
-        self.assertIs(dependent_provider2.cls, dependent_provider_copy2.cls)
-        self.assertIsNot(dependent_provider2, dependent_provider_copy2)
-
-    def test_deepcopy_overridden(self):
-        provider = self.singleton_cls(Example)
-        object_provider = providers.Object(object())
-
-        provider.override(object_provider)
-
-        provider_copy = providers.deepcopy(provider)
-        object_provider_copy = provider_copy.overridden[0]
-
-        self.assertIsNot(provider, provider_copy)
-        self.assertIs(provider.cls, provider_copy.cls)
-        self.assertIsInstance(provider, self.singleton_cls)
-
-        self.assertIsNot(object_provider, object_provider_copy)
-        self.assertIsInstance(object_provider_copy, providers.Object)
-
-    def test_deepcopy_with_sys_streams(self):
-        provider = providers.Singleton(Example)
-        provider.add_args(sys.stdin)
-        provider.add_kwargs(a2=sys.stdout)
-        provider.add_attributes(a3=sys.stderr)
-
-        provider_copy = providers.deepcopy(provider)
-
-        self.assertIsNot(provider, provider_copy)
-        self.assertIsInstance(provider_copy, providers.Singleton)
-        self.assertIs(provider.args[0], sys.stdin)
-        self.assertIs(provider.kwargs['a2'], sys.stdout)
-        self.assertIs(provider.attributes['a3'], sys.stderr)
-
-    def test_reset(self):
-        provider = self.singleton_cls(object)
-
-        instance1 = provider()
-        self.assertIsInstance(instance1, object)
-
-        provider.reset()
-
-        instance2 = provider()
-        self.assertIsInstance(instance2, object)
-
-        self.assertIsNot(instance1, instance2)
-
-    def test_reset_with_singleton(self):
-        dependent_singleton = providers.Singleton(object)
-        provider = self.singleton_cls(dict, dependency=dependent_singleton)
-
-        dependent_instance = dependent_singleton()
-        instance1 = provider()
-        self.assertIs(instance1['dependency'], dependent_instance)
-
-        provider.reset()
-
-        instance2 = provider()
-        self.assertIs(instance1['dependency'], dependent_instance)
-
-        self.assertIsNot(instance1, instance2)
-
-    def test_reset_context_manager(self):
-        singleton = self.singleton_cls(object)
-
-        instance1 = singleton()
-        with singleton.reset():
-            instance2 = singleton()
-        instance3 = singleton()
-        self.assertEqual(len({instance1, instance2, instance3}), 3)
-
-    def test_reset_context_manager_as_attribute(self):
-        singleton = self.singleton_cls(object)
-
-        with singleton.reset() as alias:
-            pass
-
-        self.assertIs(singleton, alias)
-
-    def test_full_reset(self):
-        dependent_singleton = providers.Singleton(object)
-        provider = self.singleton_cls(dict, dependency=dependent_singleton)
-
-        dependent_instance1 = dependent_singleton()
-        instance1 = provider()
-        self.assertIs(instance1['dependency'], dependent_instance1)
-
-        provider.full_reset()
-
-        dependent_instance2 = dependent_singleton()
-        instance2 = provider()
-        self.assertIsNot(instance2['dependency'], dependent_instance1)
-        self.assertIsNot(dependent_instance1, dependent_instance2)
-        self.assertIsNot(instance1, instance2)
-
-    def test_full_reset_context_manager(self):
-        class Item:
-            def __init__(self, dependency):
-                self.dependency = dependency
-
-        dependent_singleton = providers.Singleton(object)
-        singleton = self.singleton_cls(Item, dependency=dependent_singleton)
-
-        instance1 = singleton()
-        with singleton.full_reset():
-            instance2 = singleton()
-        instance3 = singleton()
-
-        self.assertEqual(len({instance1, instance2, instance3}), 3)
-        self.assertEqual(
-            len({instance1.dependency, instance2.dependency, instance3.dependency}),
-            3,
-        )
-
-    def test_full_reset_context_manager_as_attribute(self):
-        singleton = self.singleton_cls(object)
-
-        with singleton.full_reset() as alias:
-            pass
-
-        self.assertIs(singleton, alias)
 
 
 class SingletonTests(_BaseSingletonTestCase, unittest.TestCase):

tests/unit/providers/test_singletons_py3.py

@@ -0,0 +1,42 @@
+import unittest
+
+from dependency_injector import providers
+
+from .singleton_common import Example, _BaseSingletonTestCase
+
+
+class ContextLocalSingletonTests(_BaseSingletonTestCase, unittest.TestCase):
+
+    singleton_cls = providers.ContextLocalSingleton
+
+    def test_repr(self):
+        provider = providers.ContextLocalSingleton(Example)
+
+        self.assertEqual(repr(provider),
+                         '<dependency_injector.providers.'
+                         'ContextLocalSingleton({0}) at {1}>'.format(
+                             repr(Example),
+                             hex(id(provider))))
+
+    def test_reset(self):
+        provider = providers.ContextLocalSingleton(Example)
+
+        instance1 = provider()
+        self.assertIsInstance(instance1, Example)
+
+        provider.reset()
+
+        instance2 = provider()
+        self.assertIsInstance(instance2, Example)
+
+        self.assertIsNot(instance1, instance2)
+
+    def test_reset_clean(self):
+        provider = providers.ContextLocalSingleton(Example)
+        instance1 = provider()
+
+        provider.reset()
+        provider.reset()
+
+        instance2 = provider()
+        self.assertIsNot(instance1, instance2)

tox.ini

@@ -45,6 +45,7 @@ commands=
 
 [testenv:3.4]
 deps=
+    contextvars
 extras=
     flask
 commands=
@@ -52,6 +53,7 @@ commands=
 
 [testenv:3.5]
 deps=
+    contextvars
 extras=
     yaml
     flask