Raise NoFeatureFlagFound instead of handle missing flags

flask_featureflags/__init__.py

@@ -35,6 +35,11 @@ class StopCheckingFeatureFlags(Exception):
   pass
 
 
+class NoFeatureFlagFound(Exception):
+  """ Raise this when the feature flag does not exist. """
+  pass
+
+
 def AppConfigFlagHandler(feature=None):
   """ This is the default handler. It checks for feature flags in the current app's configuration.
 
@@ -63,11 +68,7 @@ class DevelopmentConfig(Config):
   try:
     return current_app.config[FEATURE_FLAGS_CONFIG][feature]
   except (AttributeError, KeyError):
-    if current_app.debug and current_app.config.get(RAISE_ERROR_ON_MISSING_FEATURES, False):
-      raise KeyError(u"No feature flag defined for {feature}".format(feature=feature))
-    else:
-      log.info(u"No feature flag defined for {feature}".format(feature=feature))
-      return False
+    raise NoFeatureFlagFound()
 
 
 class FeatureFlag(object):
@@ -93,7 +94,6 @@ def init_app(self, app):
     else:
       app.jinja_env.tests[self.JINJA_TEST_NAME] = self.check
 
-
     if not hasattr(app, 'extensions'):
       app.extensions = {}
     app.extensions[EXTENSION_NAME] = self
@@ -119,14 +119,25 @@ def check(self, feature):
     The order of handlers matters - we will immediately return True if any handler returns true.
 
     If you want to a handler to return False and stop the chain, raise the StopCheckingFeatureFlags exception."""
+    found = False
     for handler in self.handlers:
       try:
         if handler(feature):
            return True
       except StopCheckingFeatureFlags:
         return False
-    else:
-      return False
+      except NoFeatureFlagFound:
+        pass
+      else:
+        found = True
+
+    if not found:
+      if current_app.debug and current_app.config.get(RAISE_ERROR_ON_MISSING_FEATURES, False):
+        raise KeyError(u"No feature flag defined for {feature}".format(feature=feature))
+      else:
+        log.info(u"No feature flag defined for {feature}".format(feature=feature))
+
+    return False
 
 
 def is_active(feature):

tests/test_edge_cases.py

@@ -36,4 +36,5 @@ def test_running_default_handler_on_app_that_was_never_set_up_returns_false(self
     test_app = Flask(__name__)
 
     with test_app.test_request_context("/"):
-      self.assertFalse(feature_flags.AppConfigFlagHandler("BOGUS_FEATURE_FLAG"))
+      self.assertRaises(feature_flags.NoFeatureFlagFound,
+                        feature_flags.AppConfigFlagHandler, "BOGUS_FEATURE_FLAG")