bpo-41943: Fix bug where assertLogs doesn't correctly filter messages… (GH-22565)

… by level

@vsajip , @pitrou

Automerge-Triggered-By: GH:vsajip

Lib/unittest/_log.py

@@ -47,6 +47,7 @@ class _AssertLogsContext(_BaseTestCaseContext):
             logger = self.logger = logging.getLogger(self.logger_name)
         formatter = logging.Formatter(self.LOGGING_FORMAT)
         handler = _CapturingHandler()
+        handler.setLevel(self.level)
         handler.setFormatter(formatter)
         self.watcher = handler.watcher
         self.old_handlers = logger.handlers[:]

Lib/unittest/test/test_case.py

@@ -1673,6 +1673,18 @@ test case
                 with self.assertLogs(level='WARNING'):
                     log_foo.info("1")
 
+    def testAssertLogsFailureLevelTooHigh_FilterInRootLogger(self):
+        # Failure due to level too high - message propagated to root
+        with self.assertNoStderr():
+            oldLevel = log_foo.level
+            log_foo.setLevel(logging.INFO)
+            try:
+                with self.assertRaises(self.failureException):
+                    with self.assertLogs(level='WARNING'):
+                        log_foo.info("1")
+            finally:
+                log_foo.setLevel(oldLevel)
+
     def testAssertLogsFailureMismatchingLogger(self):
         # Failure due to mismatching logger (and the logged message is
         # passed through)

Misc/NEWS.d/next/Library/2020-10-07-18-36-03.bpo-41943.Pt55fT.rst

@@ -0,0 +1 @@
+Fix bug where TestCase.assertLogs doesn't correctly filter messages by level.