Support extra=None in LogAdapter.log().

Author: serhiy-storchaka

Lib/logging/__init__.py

@@ -1882,7 +1882,7 @@ def process(self, msg, kwargs):
         Normally, you'll only need to override this one method in a
         LoggerAdapter subclass for your specific needs.
         """
-        if self.merge_extra and "extra" in kwargs:
+        if self.merge_extra and kwargs.get("extra") is not None:
             if self.extra is not None:
                 kwargs["extra"] = {**self.extra, **kwargs["extra"]}
         else:

Lib/test/test_logging.py

@@ -5997,6 +5997,18 @@ def test_extra_merged(self):
         self.assertEqual(record.foo, '1')
         self.assertEqual(record.bar, '2')
 
+        self.adapter.critical('no extra')  # should not fail
+        self.assertEqual(len(self.recording.records), 2)
+        record = self.recording.records[-1]
+        self.assertEqual(record.foo, '1')
+        self.assertNotHasAttr(record, 'bar')
+
+        self.adapter.critical('none extra', extra=None)  # should not fail
+        self.assertEqual(len(self.recording.records), 3)
+        record = self.recording.records[-1]
+        self.assertEqual(record.foo, '1')
+        self.assertNotHasAttr(record, 'bar')
+
     def test_extra_merged_log_call_has_precedence(self):
         self.adapter = logging.LoggerAdapter(logger=self.logger,
                                              extra={'foo': '1'},
@@ -6012,14 +6024,21 @@ def test_extra_merged_without_extra(self):
         self.adapter = logging.LoggerAdapter(logger=self.logger,
                                              merge_extra=True)
 
-        self.adapter.critical('no extra')
-        self.assertEqual(len(self.recording.records), 1)
         self.adapter.critical('foo should be here', extra={'foo': '1'})
-        self.assertEqual(len(self.recording.records), 2)
+        self.assertEqual(len(self.recording.records), 1)
         record = self.recording.records[-1]
-        self.assertHasAttr(record, 'foo')
         self.assertEqual(record.foo, '1')
 
+        self.adapter.critical('no extra')  # should not fail
+        self.assertEqual(len(self.recording.records), 2)
+        record = self.recording.records[-1]
+        self.assertNotHasAttr(record, 'foo')
+
+        self.adapter.critical('none extra', extra=None)  # should not fail
+        self.assertEqual(len(self.recording.records), 3)
+        record = self.recording.records[-1]
+        self.assertNotHasAttr(record, 'foo')
+
 
 class PrefixAdapter(logging.LoggerAdapter):
     prefix = 'Adapter'