Refactor `container.apply_container_providers_overridings() to use container.traverse()`

docs/main/changelog.rst

@@ -9,6 +9,8 @@ follows `Semantic versioning`_
 
 Development version
 -------------------
+- Refactor ``container.apply_container_providers_overridings()`` to use ``container.traverse()``.
+  This enables deep lazy initialization of ``Container`` providers.
 - Add tests for ``Selector`` provider.
 - Add tests for ``ProvidedInstance`` and ``MethodCaller`` providers.
 - Update Makefile to make Python 3 tests to be a default test command: ``make test``.

src/dependency_injector/containers.pyx

@@ -268,9 +268,7 @@ class DynamicContainer(Container):
 
     def apply_container_providers_overridings(self):
         """Apply container providers' overridings."""
-        for provider in self.providers.values():
-            if not isinstance(provider, providers.Container):
-                continue
+        for provider in self.traverse(types=[providers.Container]):
             provider.apply_overridings()
 
 

tests/unit/providers/test_container_py2_py3.py

@@ -135,6 +135,8 @@ class ContainerTests(unittest.TestCase):
             provider.override(providers.Object('foo'))
 
     def test_lazy_overriding(self):
+        # See: https://github.com/ets-labs/python-dependency-injector/issues/354
+
         class D(containers.DeclarativeContainer):
             foo = providers.Object("foo")
 
@@ -150,4 +152,26 @@ class ContainerTests(unittest.TestCase):
         b = B(d=D())
         result = b.a().bar()
         self.assertEqual(result, 'foo++')
-        # See: https://github.com/ets-labs/python-dependency-injector/issues/354
+
+    def test_lazy_overriding_deep(self):
+        # Extended version of test_lazy_overriding()
+
+        class D(containers.DeclarativeContainer):
+            foo = providers.Object("foo")
+
+        class C(containers.DeclarativeContainer):
+            d = providers.DependenciesContainer()
+            bar = providers.Callable(lambda f: f + "++", d.foo.provided)
+
+        class A(containers.DeclarativeContainer):
+            d = providers.DependenciesContainer()
+            c = providers.Container(C, d=d)
+
+        class B(containers.DeclarativeContainer):
+            d = providers.DependenciesContainer()
+
+            a = providers.Container(A, d=d)
+
+        b = B(d=D())
+        result = b.a().c().bar()
+        self.assertEqual(result, 'foo++')