Add Configuration.from_env() method + refactoring

docs/main/changelog.rst

@@ -9,9 +9,10 @@ follows `Semantic versioning`_
 
 Development version
 -------------------
-- Add ``Configuration.from_yaml()`` method to load configuration from yaml file.
+- Add ``Configuration.from_yaml()`` method to load configuration from the yaml file.
-- Add ``Configuration.from_ini()`` method to load configuration from ini file.
+- Add ``Configuration.from_ini()`` method to load configuration from the ini file.
-- Add ``Configuration.from_dict()`` method to load configuration from dictionary.
+- Add ``Configuration.from_dict()`` method to load configuration from the dictionary.
+- Add ``Configuration.from_env()`` method to load configuration from the environment variable.
 - Add default value for ``name`` argument of ``Configuration`` provider.
 - Remove undocumented positional parameter of ``DependenciesContainer`` provider.
 

src/dependency_injector/providers.pyx

@@ -4,6 +4,7 @@ Powered by Cython.
 """
 
 import copy
+import os
 import sys
 import types
 import threading
@@ -1164,23 +1165,8 @@ cdef class Configuration(Object):
         """
         self.override(value)
 
-    def from_dict(self, options):
-        """Load configuration from dictionary.
-
-        Loaded configuration is merged recursively over current configuration.
-
-        :param options: Configuration options.
-        :type options: dict
-
-        :rtype: None
-        """
-        current_config = self.__call__()
-        if not current_config:
-            current_config = {}
-        self.override(merge_dicts(current_config, options))
-
     def from_ini(self, filepath):
-        """Load configuration from ini file.
+        """Load configuration from the ini file.
 
         Loaded configuration is merged recursively over current configuration.
 
@@ -1202,7 +1188,7 @@ cdef class Configuration(Object):
         self.override(merge_dicts(current_config, config))
 
     def from_yaml(self, filepath):
-        """Load configuration from yaml file.
+        """Load configuration from the yaml file.
 
         Loaded configuration is merged recursively over current configuration.
 
@@ -1226,6 +1212,35 @@ cdef class Configuration(Object):
             current_config = {}
         self.override(merge_dicts(current_config, config))
 
+    def from_dict(self, options):
+        """Load configuration from the dictionary.
+
+        Loaded configuration is merged recursively over current configuration.
+
+        :param options: Configuration options.
+        :type options: dict
+
+        :rtype: None
+        """
+        current_config = self.__call__()
+        if not current_config:
+            current_config = {}
+        self.override(merge_dicts(current_config, options))
+
+    def from_env(self, name, default=None):
+        """Load configuration value from the environment variable.
+
+        :param name: Name of the environment variable.
+        :type name: str
+
+        :param default: Default value that is used if environment variable does not exist.
+        :type default: str
+
+        :rtype: None
+        """
+        value = os.getenv(name, default)
+        self.override(value)
+
     def _create_children(self, value):
         children = dict()
 

tests/unit/providers/test_configuration_py2_py3.py

@@ -257,66 +257,6 @@ class ConfigLinkingTests(unittest.TestCase):
         self.assertEqual(services.value_getter(), 'services2')
 
 
-class ConfigFromDict(unittest.TestCase):
-
-    def setUp(self):
-        self.config = providers.Configuration(name='config')
-
-        self.config_options_1 = {
-            'section1': {
-                'value1': '1',
-            },
-            'section2': {
-                'value2': '2',
-            },
-        }
-        self.config_options_2 = {
-            'section1': {
-                'value1': '11',
-                'value11': '11',
-            },
-            'section3': {
-                'value3': '3',
-            },
-        }
-
-    def test(self):
-        self.config.from_dict(self.config_options_1)
-
-        self.assertEqual(self.config(), {'section1': {'value1': '1'}, 'section2': {'value2': '2'}})
-        self.assertEqual(self.config.section1(), {'value1': '1'})
-        self.assertEqual(self.config.section1.value1(), '1')
-        self.assertEqual(self.config.section2(), {'value2': '2'})
-        self.assertEqual(self.config.section2.value2(), '2')
-
-    def test_merge(self):
-        self.config.from_dict(self.config_options_1)
-        self.config.from_dict(self.config_options_2)
-
-        self.assertEqual(
-            self.config(),
-            {
-                'section1': {
-                    'value1': '11',
-                    'value11': '11',
-                },
-                'section2': {
-                    'value2': '2',
-                },
-                'section3': {
-                    'value3': '3',
-                },
-            },
-        )
-        self.assertEqual(self.config.section1(), {'value1': '11', 'value11': '11'})
-        self.assertEqual(self.config.section1.value1(), '11')
-        self.assertEqual(self.config.section1.value11(), '11')
-        self.assertEqual(self.config.section2(), {'value2': '2'})
-        self.assertEqual(self.config.section2.value2(), '2')
-        self.assertEqual(self.config.section3(), {'value3': '3'})
-        self.assertEqual(self.config.section3.value3(), '3')
-
-
 class ConfigFromIniTests(unittest.TestCase):
 
     def setUp(self):
@@ -472,3 +412,89 @@ class ConfigFromYamlTests(unittest.TestCase):
             'Install PyYAML or install Dependency Injector with yaml extras: '
             '"pip install dependency-injector[yaml]"',
         )
+
+
+class ConfigFromDict(unittest.TestCase):
+
+    def setUp(self):
+        self.config = providers.Configuration(name='config')
+
+        self.config_options_1 = {
+            'section1': {
+                'value1': '1',
+            },
+            'section2': {
+                'value2': '2',
+            },
+        }
+        self.config_options_2 = {
+            'section1': {
+                'value1': '11',
+                'value11': '11',
+            },
+            'section3': {
+                'value3': '3',
+            },
+        }
+
+    def test(self):
+        self.config.from_dict(self.config_options_1)
+
+        self.assertEqual(self.config(), {'section1': {'value1': '1'}, 'section2': {'value2': '2'}})
+        self.assertEqual(self.config.section1(), {'value1': '1'})
+        self.assertEqual(self.config.section1.value1(), '1')
+        self.assertEqual(self.config.section2(), {'value2': '2'})
+        self.assertEqual(self.config.section2.value2(), '2')
+
+    def test_merge(self):
+        self.config.from_dict(self.config_options_1)
+        self.config.from_dict(self.config_options_2)
+
+        self.assertEqual(
+            self.config(),
+            {
+                'section1': {
+                    'value1': '11',
+                    'value11': '11',
+                },
+                'section2': {
+                    'value2': '2',
+                },
+                'section3': {
+                    'value3': '3',
+                },
+            },
+        )
+        self.assertEqual(self.config.section1(), {'value1': '11', 'value11': '11'})
+        self.assertEqual(self.config.section1.value1(), '11')
+        self.assertEqual(self.config.section1.value11(), '11')
+        self.assertEqual(self.config.section2(), {'value2': '2'})
+        self.assertEqual(self.config.section2.value2(), '2')
+        self.assertEqual(self.config.section3(), {'value3': '3'})
+        self.assertEqual(self.config.section3.value3(), '3')
+
+
+class ConfigFromEnvTests(unittest.TestCase):
+
+    def setUp(self):
+        self.config = providers.Configuration(name='config')
+        os.environ['CONFIG_TEST_ENV'] = 'test-value'
+
+    def tearDown(self):
+        del self.config
+        del os.environ['CONFIG_TEST_ENV']
+
+    def test(self):
+        self.config.from_env('CONFIG_TEST_ENV')
+        self.assertEqual(self.config(), 'test-value')
+
+    def test_default(self):
+        self.config.from_env('UNDEFINED_ENV', 'default-value')
+        self.assertEqual(self.config(), 'default-value')
+
+    def test_with_children(self):
+        self.config.section1.value1.from_env('CONFIG_TEST_ENV')
+
+        self.assertIsNone(self.config())
+        self.assertIsNone(self.config.section1())
+        self.assertEqual(self.config.section1.value1(), 'test-value')