Add config models and a configuration service to configure LTI Consumer.

common/lib/xmodule/xmodule/services.py

@@ -1,6 +1,9 @@
 """
 Module contains various XModule/XBlock services
 """
+import inspect
+
+from config_models.models import ConfigurationModel
 from django.conf import settings
 
 
@@ -61,3 +64,32 @@ class SettingsService(object):
         xblock_settings_bucket = getattr(block, self.xblock_settings_bucket_selector, block.unmixed_class.__name__)
         xblock_settings = settings.XBLOCK_SETTINGS if hasattr(settings, "XBLOCK_SETTINGS") else {}
         return xblock_settings.get(xblock_settings_bucket, actual_default)
+
+
+# TODO: ConfigurationService and its usage will be removed as a part of EDUCATOR-121
+# reference: https://openedx.atlassian.net/browse/EDUCATOR-121
+class ConfigurationService(object):
+    """
+    An XBlock service to talk with the Configuration Models. This service should provide
+    a pathway to Configuration Model which is designed to configure the corresponding XBlock.
+    """
+    def __init__(self, configuration_model):
+        """
+        Class initializer, this exposes configuration model to XBlock.
+
+        Arguments:
+            configuration_model (ConfigurationModel): configurations for an XBlock
+
+        Raises:
+            exception (ValueError): when configuration_model is not a subclass of
+            ConfigurationModel.
+        """
+        if not (inspect.isclass(configuration_model) and issubclass(configuration_model, ConfigurationModel)):
+            raise ValueError(
+                "Expected ConfigurationModel got {0} of type {1}".format(
+                    configuration_model,
+                    type(configuration_model)
+                )
+            )
+
+        self.configuration = configuration_model

common/lib/xmodule/xmodule/tests/test_services.py

@@ -6,11 +6,12 @@ import ddt
 import mock
 from unittest import TestCase
 
+from config_models.models import ConfigurationModel
 from django.conf import settings
 from django.test.utils import override_settings
 
 from xblock.runtime import Mixologist
-from xmodule.services import SettingsService
+from xmodule.services import ConfigurationService, SettingsService
 
 
 class _DummyBlock(object):
@@ -18,6 +19,20 @@ class _DummyBlock(object):
     pass
 
 
+class DummyConfig(ConfigurationModel):
+    """
+    Dummy Configuration
+    """
+    pass
+
+
+class DummyUnexpected(object):
+    """
+    Dummy Unexpected Class
+    """
+    pass
+
+
 @ddt.ddt
 class TestSettingsService(TestCase):
     """ Test SettingsService """
@@ -76,3 +91,23 @@ class TestSettingsService(TestCase):
         block = mixologist.mix(_DummyBlock)
         self.assertEqual(settings.XBLOCK_SETTINGS, {"_DummyBlock": [1, 2, 3]})
         self.assertEqual(self.settings_service.get_settings_bucket(block), [1, 2, 3])
+
+
+class TestConfigurationService(TestCase):
+    """
+    Tests for ConfigurationService
+    """
+    def test_given_unexpected_class_throws_value_error(self):
+        """
+        Test that instantiating ConfigurationService raises exception on passing
+        a class which is not subclass of ConfigurationModel.
+        """
+        with self.assertRaises(ValueError):
+            ConfigurationService(DummyUnexpected)
+
+    def test_configuration_service(self):
+        """
+        Test the correct configuration on instantiating ConfigurationService.
+        """
+        config_service = ConfigurationService(DummyConfig)
+        self.assertEqual(config_service.configuration, DummyConfig)