Fixes reporting the error when drivers have the same name

Resolves issue #25

Change-Id: I944800fc2da0018b5b3bb076d296c38126fe97bf

docs/source/history.rst

@@ -2,6 +2,11 @@
  History
 =========
 
+dev
+
+- Fixes an exception when reporting on an error where multiple drivers
+  have the same name (:issue:`25`, solution provided by clayg).
+
 0.11
 
 - Fixes logging configuration under Python 2.6 with a NullHandler.

stevedore/driver.py

@@ -36,7 +36,8 @@ class DriverManager(NamedExtensionManager):
         if len(self.extensions) > 1:
             raise RuntimeError('Multiple %r drivers found: %s' %
                                (namespace,
-                                ','.join('%s:%s' % (e.module_name, e.attrs[0])
+                                ','.join('%s:%s' % (e.entry_point.module_name,
+                                                    e.entry_point.attrs[0])
                                          for e in self.extensions))
                                )
 

stevedore/tests/test_driver.py

@@ -1,6 +1,9 @@
 """Tests for stevedore.extension
 """
 
+import mock
+import pkg_resources
+
 from stevedore import driver
 from stevedore.tests import test_extension
 
@@ -38,3 +41,21 @@ def test_no_drivers():
         driver.DriverManager('stevedore.test.extension.none', 't1')
     except RuntimeError as err:
         assert "No 'stevedore.test.extension.none' driver found" in str(err)
+
+
+def test_multiple_drivers():
+    # The idea for this test was contributed by clayg:
+    # https://gist.github.com/clayg/6311348
+    fep_name = 'stevedore.extension.ExtensionManager._find_entry_points'
+    with mock.patch(fep_name) as fep:
+        fep.return_value = [
+            pkg_resources.EntryPoint.parse('backend = pkg1:driver'),
+            pkg_resources.EntryPoint.parse('backend = pkg2:driver'),
+        ]
+        for ep in fep.return_value:
+            ep.load = lambda: 'pkg backend'
+        try:
+            driver.DriverManager('stevedore.test.multiple_drivers', 'backend')
+        except RuntimeError as err:
+            assert "Multiple" in str(err), str(err)
+        fep.assert_called_with('stevedore.test.multiple_drivers')