Update from_dict() method

src/dependency_injector/providers.pyx

@@ -1387,7 +1387,7 @@ cdef class ConfigurationOption(Provider):
             current_config = {}
         self.override(merge_dicts(current_config, config))
 
-    def from_dict(self, options):
+    def from_dict(self, options, required=UNDEFINED):
         """Load configuration from the dictionary.
 
         Loaded configuration is merged recursively over existing configuration.
@@ -1395,14 +1395,24 @@ cdef class ConfigurationOption(Provider):
         :param options: Configuration options.
         :type options: dict
 
+        :param required: When required is True, raise an exception if dictionary is empty.
+        :type required: bool
+
         :rtype: None
         """
-        if self._is_strict_mode_enabled() and not options:
+        if required is not False \
+                and (self._is_strict_mode_enabled() or required is True) \
+                and not options:
             raise ValueError('Can not use empty dictionary')
 
-        current_config = self.__call__()
-        if not current_config:
+        try:
+            current_config = self.__call__()
+        except Error:
             current_config = {}
+        else:
+            if not current_config:
+                current_config = {}
+
         self.override(merge_dicts(current_config, options))
 
     def from_env(self, name, default=UNDEFINED):
@@ -1705,7 +1715,7 @@ cdef class Configuration(Object):
             current_config = {}
         self.override(merge_dicts(current_config, config))
 
-    def from_dict(self, options):
+    def from_dict(self, options, required=UNDEFINED):
         """Load configuration from the dictionary.
 
         Loaded configuration is merged recursively over existing configuration.
@@ -1713,9 +1723,14 @@ cdef class Configuration(Object):
         :param options: Configuration options.
         :type options: dict
 
+        :param required: When required is True, raise an exception if file does not exist.
+        :type required: bool
+
         :rtype: None
         """
-        if self._is_strict_mode_enabled() and not options:
+        if required is not False \
+                and (self._is_strict_mode_enabled() or required is True) \
+                and not options:
             raise ValueError('Can not use empty dictionary')
 
         current_config = self.__call__()

tests/unit/providers/test_configuration_py2_py3.py

@@ -737,24 +737,6 @@ class ConfigFromDict(unittest.TestCase):
         self.assertEqual(self.config.section2(), {'value2': '2'})
         self.assertEqual(self.config.section2.value2(), '2')
 
-    def test_empty_dict(self):
-        self.config.from_dict({})
-        self.assertEqual(self.config(), {})
-
-    def test_option_empty_dict(self):
-        self.config.option.from_dict({})
-        self.assertEqual(self.config.option(), {})
-
-    def test_empty_dict_in_strict_mode(self):
-        self.config = providers.Configuration(strict=True)
-        with self.assertRaises(ValueError):
-            self.config.from_dict({})
-
-    def test_option_empty_dict_in_strict_mode(self):
-        self.config = providers.Configuration(strict=True)
-        with self.assertRaises(ValueError):
-            self.config.option.from_dict({})
-
     def test_merge(self):
         self.config.from_dict(self.config_options_1)
         self.config.from_dict(self.config_options_2)
@@ -782,6 +764,43 @@ class ConfigFromDict(unittest.TestCase):
         self.assertEqual(self.config.section3(), {'value3': '3'})
         self.assertEqual(self.config.section3.value3(), '3')
 
+    def test_empty_dict(self):
+        self.config.from_dict({})
+        self.assertEqual(self.config(), {})
+
+    def test_option_empty_dict(self):
+        self.config.option.from_dict({})
+        self.assertEqual(self.config.option(), {})
+
+    def test_empty_dict_in_strict_mode(self):
+        self.config = providers.Configuration(strict=True)
+        with self.assertRaises(ValueError):
+            self.config.from_dict({})
+
+    def test_option_empty_dict_in_strict_mode(self):
+        self.config = providers.Configuration(strict=True)
+        with self.assertRaises(ValueError):
+            self.config.option.from_dict({})
+
+    def test_required_empty_dict(self):
+        with self.assertRaises(ValueError):
+            self.config.from_dict({}, required=True)
+
+    def test_required_option_empty_dict(self):
+        with self.assertRaises(ValueError):
+            self.config.option.from_dict({}, required=True)
+
+    def test_not_required_empty_dict_strict_mode(self):
+        self.config = providers.Configuration(strict=True)
+        self.config.from_dict({}, required=False)
+        self.assertEqual(self.config(), {})
+
+    def test_not_required_option_empty_dict_strict_mode(self):
+        self.config = providers.Configuration(strict=True)
+        self.config.option.from_dict({}, required=False)
+        self.assertEqual(self.config.option(), {})
+        self.assertEqual(self.config(), {'option': {}})
+
 
 class ConfigFromEnvTests(unittest.TestCase):