Load extensions before checking enabled status

Go ahead and load the extension entry point so the
check function can interrogate it about whether it
should be enabled or not.

Signed-off-by: Doug Hellmann <doug.hellmann@dreamhost.com>

stevedore/enabled.py

@@ -41,9 +41,10 @@ class EnabledExtensionManager(ExtensionManager):
             )
 
     def _load_one_plugin(self, ep, invoke_on_load, invoke_args, invoke_kwds):
-        if not self.check_func(ep):
-            LOG.debug('ignoring extension %r', ep.name)
-            return None
-        return super(EnabledExtensionManager, self)._load_one_plugin(
+        ext = super(EnabledExtensionManager, self)._load_one_plugin(
             ep, invoke_on_load, invoke_args, invoke_kwds,
             )
+        if ext and not self.check_func(ext):
+            LOG.debug('ignoring extension %r', ep.name)
+            return None
+        return ext

stevedore/tests/test_enabled.py

@@ -13,3 +13,17 @@ def test_enabled():
         )
     assert len(em.extensions) == 1
     assert em.names() == ['t2']
+
+
+def test_enabled_after_load():
+    def check_enabled(ext):
+        return ext.obj and ext.name == 't2'
+    em = enabled.EnabledExtensionManager(
+        'stevedore.test.extension',
+        check_enabled,
+        invoke_on_load=True,
+        invoke_args=('a',),
+        invoke_kwds={'b': 'B'},
+        )
+    assert len(em.extensions) == 1
+    assert em.names() == ['t2']