Fix required configuration option cache invalidation

src/dependency_injector/providers.pxd

@@ -117,6 +117,7 @@ cdef class ConfigurationOption(Provider):
     cdef Configuration _root
     cdef dict _children
     cdef bint _required
+    cdef object _required_option
     cdef object _cache
 
 

src/dependency_injector/providers.pyx

@@ -1522,6 +1522,7 @@ cdef class ConfigurationOption(Provider):
         self._root = root
         self._children = {}
         self._required = required
+        self._required_option = None
         self._cache = UNDEFINED
         super().__init__()
 
@@ -1537,6 +1538,7 @@ cdef class ConfigurationOption(Provider):
         copied._root = deepcopy(self._root, memo)
         copied._children = deepcopy(self._children, memo)
         copied._required = self._required
+        copied._required_option = deepcopy(self._required_option, memo)
         self._copy_overridings(copied, memo)
         return copied
 
@@ -1604,7 +1606,11 @@ cdef class ConfigurationOption(Provider):
         return TypedConfigurationOption(callback, self, *args, **kwargs)
 
     def required(self):
-        return self.__class__(self._name, self._root, required=True)
+        if self._required:
+            return self
+        if self._required_option is None:
+            self._required_option = self.__class__(self._name, self._root, required=True)
+        return self._required_option
 
     def is_required(self):
         return self._required
@@ -1626,6 +1632,9 @@ cdef class ConfigurationOption(Provider):
         for provider in self._children.values():
             provider.reset_cache()
 
+        if self._required_option is not None:
+            self._required_option.reset_cache()
+
         for provider in self.overrides:
             if isinstance(provider, (Configuration, ConfigurationOption)):
                 provider.reset_cache()

tests/unit/providers/configuration/test_config_py2_py3.py

@@ -121,6 +121,24 @@ def test_required(config):
         provider()
 
 
+def test_required_cache_is_reset_after_option_override():
+    class Container(containers.DeclarativeContainer):
+        config = providers.Configuration()
+        singleton = providers.Singleton(dict, value=config.a.required())
+
+    container = Container()
+    container.config.a.from_value("initial")
+
+    assert container.singleton() == {"value": "initial"}
+
+    with container.config.a.override("overridden"):
+        container.singleton.reset()
+        assert container.singleton() == {"value": "overridden"}
+
+    container.singleton.reset()
+    assert container.singleton() == {"value": "initial"}
+
+
 def test_required_defined_none(config):
     provider = providers.Callable(
         lambda value: value,