Remove unnecessary checks and reformat NoAppException messages

flask/cli.py

@@ -37,7 +37,7 @@ def find_best_app(module):
     # Search for the most common names first.
     for attr_name in 'app', 'application':
         app = getattr(module, attr_name, None)
-        if app is not None and isinstance(app, Flask):
+        if isinstance(app, Flask):
             return app
 
     # Otherwise find the only object that is a Flask instance.
@@ -50,21 +50,23 @@ def find_best_app(module):
     # Search for app factory callables.
     for attr_name in 'create_app', 'make_app':
         app_factory = getattr(module, attr_name, None)
-        if app_factory is not None and callable(app_factory):
+        if callable(app_factory):
             try:
                 app = app_factory()
-                if app is not None and isinstance(app, Flask):
+                if isinstance(app, Flask):
                     return app
             except TypeError:
-                raise NoAppException('Auto-detected "%s()" in module "%s", '
-                                     'but could not call it without '
-                                     'specifying arguments.'
-                                     % (attr_name, module.__name__))
-
-    raise NoAppException('Failed to find application in module "%s".  Are '
-                         'you sure it contains a Flask application?  Maybe '
-                         'you wrapped it in a WSGI middleware or you are '
-                         'using a factory function.' % module.__name__)
+                raise NoAppException(
+                    'Auto-detected "{callable}()" in module "{module}", but '
+                    'could not call it without specifying arguments.'
+                    .format(callable=attr_name,
+                            module=module.__name__))
+
+    raise NoAppException(
+        'Failed to find application in module "{module}".  Are you sure '
+        'it contains a Flask application?  Maybe you wrapped it in a WSGI '
+        'middleware or you are using a factory function.'
+        .format(module=module.__name__))
 
 
 def prepare_exec_for_file(filename):