gh-117975: Ensure flush level is checked when configuring a logging MemoryHandler. (GH-117976)

Lib/logging/config.py

@@ -761,18 +761,20 @@ class DictConfigurator(BaseConfigurator):
                 klass = cname
             else:
                 klass = self.resolve(cname)
-            if issubclass(klass, logging.handlers.MemoryHandler) and\
-                'target' in config:
-                # Special case for handler which refers to another handler
-                try:
-                    tn = config['target']
-                    th = self.config['handlers'][tn]
-                    if not isinstance(th, logging.Handler):
-                        config.update(config_copy)  # restore for deferred cfg
-                        raise TypeError('target not configured yet')
-                    config['target'] = th
-                except Exception as e:
-                    raise ValueError('Unable to set target handler %r' % tn) from e
+            if issubclass(klass, logging.handlers.MemoryHandler):
+                if 'flushLevel' in config:
+                    config['flushLevel'] = logging._checkLevel(config['flushLevel'])
+                if 'target' in config:
+                    # Special case for handler which refers to another handler
+                    try:
+                        tn = config['target']
+                        th = self.config['handlers'][tn]
+                        if not isinstance(th, logging.Handler):
+                            config.update(config_copy)  # restore for deferred cfg
+                            raise TypeError('target not configured yet')
+                        config['target'] = th
+                    except Exception as e:
+                        raise ValueError('Unable to set target handler %r' % tn) from e
             elif issubclass(klass, logging.handlers.QueueHandler):
                 # Another special case for handler which refers to other handlers
                 # if 'handlers' not in config:

Lib/test/test_logging.py

@@ -3036,6 +3036,30 @@ class ConfigDictTest(BaseTest):
         },
     }
 
+    config18  = {
+        "version": 1,
+        "handlers": {
+            "console": {
+                "class": "logging.StreamHandler",
+                "level": "DEBUG",
+            },
+            "buffering": {
+                "class": "logging.handlers.MemoryHandler",
+                "capacity": 5,
+                "target": "console",
+                "level": "DEBUG",
+                "flushLevel": "ERROR"
+            }
+        },
+        "loggers": {
+            "mymodule": {
+                "level": "DEBUG",
+                "handlers": ["buffering"],
+                "propagate": "true"
+            }
+        }
+    }
+
     bad_format = {
         "version": 1,
         "formatters": {
@@ -3522,6 +3546,11 @@ class ConfigDictTest(BaseTest):
         h = logging._handlers['hand1']
         self.assertEqual(h.formatter.custom_property, 'value')
 
+    def test_config18_ok(self):
+        self.apply_config(self.config18)
+        handler = logging.getLogger('mymodule').handlers[0]
+        self.assertEqual(handler.flushLevel, logging.ERROR)
+
     def setup_via_listener(self, text, verify=None):
         text = text.encode("utf-8")
         # Ask for a randomly assigned port (by using port 0)