Wrong provider name in answers.conf, exits AtomicApp with readable error

atomicapp/nulecule/lib.py

@@ -5,9 +5,11 @@
                                  LOGGER_COCKPIT,
                                  NAME_KEY,
                                  DEFAULTNAME_KEY,
-                                 PROVIDER_KEY)
+                                 PROVIDER_KEY,
+                                 PROVIDERS)
 from atomicapp.utils import Utils
 from atomicapp.plugin import Plugin
+from atomicapp.nulecule.exceptions import NuleculeException
 
 cockpit_logger = logging.getLogger(LOGGER_COCKPIT)
 
@@ -101,6 +103,11 @@ def get_provider(self, provider_key=None, dry=False):
         if provider_key is None:
             provider_key = self.config.get(GLOBAL_CONF)[PROVIDER_KEY]
         provider_class = self.plugin.getProvider(provider_key)
+        if provider_class is None:
+            raise NuleculeException("Invalid Provider - '{}', provided in "
+                                    "answers.conf (choose from {})"
+                                    .format(provider_key, ', '
+                                                          .join(PROVIDERS)))
         return provider_key, provider_class(
             self.get_context(), self.basepath, dry)
 

tests/units/nulecule/test_lib.py

@@ -0,0 +1,40 @@
+import mock
+import unittest
+
+from atomicapp.nulecule.lib import NuleculeBase
+from atomicapp.nulecule.exceptions import NuleculeException
+
+
+class TestNuleculeBaseGetProvider(unittest.TestCase):
+    """ Test NuleculeBase get_provider"""
+    def test_get_provider_success(self):
+        """
+        Test if get_provider method when passed a particular valid key returns
+        the corresponding class.
+        """
+        nb = NuleculeBase(params = [], basepath = '', namespace = '')
+        provider_key = u'openshift'
+        # method `get_provider` will read from this config, we give it here
+        # since we have neither provided it before nor it is auto-generated
+        nb.config = {u'general': {u'provider': provider_key}}
+
+        return_provider = mock.Mock()
+        # mocking return value of method plugin.getProvider,because it returns
+        # provider class and that class gets called with values
+        nb.plugin.getProvider = mock.Mock(return_value=return_provider)
+        ret_provider_key, ret_provider = nb.get_provider()
+        self.assertEqual(provider_key, ret_provider_key)
+        return_provider.assert_called_with({u'provider': provider_key}, 
+                                            '', False)
+
+    def test_get_provider_failure(self):
+        """
+        Test if get_provider method when passed an invalid key raises an
+        exception.
+        """
+        nb = NuleculeBase(params = [], basepath = '', namespace = '')
+        # purposefully give the wrong provider key
+        provider_key = u'mesos'
+        nb.config = {u'general': {u'provider': provider_key}}
+        with self.assertRaises(NuleculeException):
+            nb.get_provider() 

tests/units/test_plugin.py

@@ -0,0 +1,27 @@
+import mock
+import unittest
+
+from atomicapp.plugin import Plugin
+
+class TestPluginGetProvider(unittest.TestCase):
+
+    """Test Plugin getProvider"""
+    def test_getProvider(self):
+        """
+        Test if getProvider is returning appropriate classes to the
+        corresponding keys.
+        """
+        p = Plugin()
+
+        docker_mock = mock.Mock()
+        kubernetes_mock = mock.Mock()
+        # keep some mock objects in place of the actual corresponding
+        # classes, getProvider reads from `plugins` dict.
+        p.plugins = {
+            'docker': docker_mock,
+            'kubernetes': kubernetes_mock,
+        }
+        self.assertEqual(p.getProvider('docker'), docker_mock)
+        self.assertEqual(p.getProvider('kubernetes'), kubernetes_mock)
+        # if non-existent key provided
+        self.assertEqual(p.getProvider('some_random'), None)