driver extension manager test instance factory

4 files changed, 82 insertions, 6 deletions

diff --git a/stevedore/driver.py b/stevedore/driver.py
index 54cdcae..d8bcd12 100644
--- a/stevedore/driver.py
+++ b/stevedore/driver.py
@@ -30,16 +30,49 @@ class DriverManager(NamedExtensionManager):
             invoke_args=invoke_args,
             invoke_kwds=invoke_kwds,
         )
+
+    @classmethod
+    def make_test_instance(cls, available_extensions, name,
+                           propagate_map_exceptions=False):
+        """Construct a test DriverManager
+
+        Test instances are passed a list of extensions to work from rather
+        than loading them from entry points.  DriverManager test instances use
+        the name argument to determine which of the available_extensions should
+        be used as the driver.
+
+        :param available_extensions: Pre-configured Extension instances
+            available for use
+        :type available_extensions: list of
+            :class:`~stevedore.extension.Extension`
+        :param name: The name of the driver to use.
+        :type name: str
+        :param propagate_map_exceptions: Boolean controlling whether exceptions
+            are propagated up through the map call or whether they are logged
+            and then ignored
+        :type propagate_map_exceptions: bool
+        :return: The manager instance, initialized for testing
+
+        """
+
+        o = super(DriverManager, cls).make_test_instance(
+            available_extensions, [name],
+            propagate_map_exceptions=propagate_map_exceptions)
+        return o
+
+    def _init_plugins(self, extensions, propagate_map_exceptions=False):
+        super(DriverManager, self)._init_plugins(extensions)
+
         if not self.extensions:
+            name = self._names[0]
             raise RuntimeError('No %r driver found, looking for %r' %
-                               (namespace, name))
+                               (self.namespace, name))
         if len(self.extensions) > 1:
             discovered_drivers = ','.join(e.entry_point_target
                                           for e in self.extensions)
 
             raise RuntimeError('Multiple %r drivers found: %s' %
-                               (namespace, discovered_drivers))
-
+                               (self.namespace, discovered_drivers))
 
     def __call__(self, func, *args, **kwds):
         """Invokes func() for the single loaded extension.
diff --git a/stevedore/named.py b/stevedore/named.py
index 9708f99..0b1ce97 100644
--- a/stevedore/named.py
+++ b/stevedore/named.py
@@ -46,7 +46,7 @@ class NamedExtensionManager(ExtensionManager):
         )
 
     @classmethod
-    def make_test_instance(cls, available_extensions, names,
+    def make_test_instance(cls, available_extensions, names=None,
                            name_order=False, propagate_map_exceptions=False):
         """Construct a test NamedExtensionManager
 
@@ -73,6 +73,7 @@ class NamedExtensionManager(ExtensionManager):
         """
 
         o = cls.__new__(cls)
+        o.namespace = 'TESTING'
         o._names = names
         o._name_order = name_order
 
@@ -80,6 +81,7 @@ class NamedExtensionManager(ExtensionManager):
         # happens in _load_one_plugin
         extensions = [extension for extension in available_extensions
                       if extension.name in names]
+
         o._init_plugins(extensions,
                         propagate_map_exceptions=propagate_map_exceptions)
         return o
diff --git a/stevedore/tests/test_driver.py b/stevedore/tests/test_driver.py
index 70ec54c..df43110 100644
--- a/stevedore/tests/test_driver.py
+++ b/stevedore/tests/test_driver.py
@@ -1,13 +1,21 @@
 """Tests for stevedore.extension
 """
+from mock import Mock, sentinel
+from nose.tools import raises
 
 import mock
 import pkg_resources
 
 from stevedore import driver
+from stevedore.extension import Extension
 from stevedore.tests import test_extension
 
 
+mock_entry_point = Mock(module_name='test.extension', attrs=['obj'])
+a_driver = Extension('test_driver', mock_entry_point, sentinel.driver_plugin,
+                     sentinel.driver_obj)
+
+
 def test_detect_plugins():
     em = driver.DriverManager('stevedore.test.extension', 't1')
     names = sorted(em.names())
@@ -59,3 +67,37 @@ def test_multiple_drivers():
         except RuntimeError as err:
             assert "Multiple" in str(err), str(err)
         fep.assert_called_with('stevedore.test.multiple_drivers')
+
+
+@raises(RuntimeError)
+def test_instance_driver_not_found_should_raise():
+    extension = Extension('a_driver', None, None, None)
+    driver.DriverManager.make_test_instance(
+        [extension], 'this_is_not_the_driver_you_are_looking_for')
+
+
+@raises(RuntimeError)
+def test_instance_multiple_drivers_found_should_raise():
+    extension = Extension('test_driver', mock_entry_point, None, None)
+    copycat = Extension('test_driver', mock_entry_point, None, None)
+
+    driver.DriverManager.make_test_instance([extension, copycat],
+                                            'test_driver')
+
+
+def test_instance_should_find_named_driver():
+    em = driver.DriverManager.make_test_instance([a_driver], 'test_driver')
+    assert ['test_driver'] == em.names()
+
+
+def test_instance_call():
+    def invoke(ext, *args, **kwds):
+        return (ext.name, args, kwds)
+    em = driver.DriverManager.make_test_instance([a_driver], 'test_driver')
+    result = em(invoke, 'a', b='C')
+    assert result == ('test_driver', ('a',), {'b': 'C'})
+
+
+def test_instance_driver():
+    em = driver.DriverManager.make_test_instance([a_driver], 'test_driver')
+    assert sentinel.driver_obj == em.driver
diff --git a/stevedore/tests/test_test_manager.py b/stevedore/tests/test_test_manager.py
index 3046127..2dd42c0 100644
--- a/stevedore/tests/test_test_manager.py
+++ b/stevedore/tests/test_test_manager.py
@@ -1,7 +1,6 @@
 from mock import Mock
 from nose.tools import raises
-from stevedore import (ExtensionManager, NamedExtensionManager, HookManager,
-                       EnabledExtensionManager, DriverManager)
+from stevedore import (ExtensionManager, NamedExtensionManager, HookManager)
 from stevedore.extension import Extension