Fix caplog handler level restoration (swev-id: pytest-dev__pytest-7571)

src/_pytest/logging.py

@@ -673,6 +673,8 @@ def pytest_runtest_logreport(self) -> None:
 
     def _runtest_for(self, item: nodes.Item, when: str) -> Generator[None, None, None]:
         """Implements the internals of pytest_runtest_xxx() hook."""
+        if when == "setup" and self.log_level is None:
+            self.caplog_handler.setLevel(logging.NOTSET)
         with catching_logs(
             self.caplog_handler, level=self.log_level,
         ) as caplog_handler, catching_logs(

testing/logging/test_fixture.py

@@ -236,6 +236,97 @@ def test_log_level_override(request, caplog):
     assert result.ret == 1
 
 
+def test_caplog_handler_level_restored_between_tests(testdir):
+    testdir.makepyfile(
+        """
+        import logging
+
+        def test_sets_custom_level(caplog):
+            caplog.set_level(42)
+            assert caplog.handler.level == 42
+
+        def test_handler_level_restored(caplog):
+            assert caplog.handler.level == logging.NOTSET
+        """
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=2)
+
+
+def test_caplog_logger_specific_override_restores_handler_level(testdir):
+    testdir.makepyfile(
+        """
+        import logging
+
+        def test_override_specific_logger(caplog):
+            logger = logging.getLogger('example')
+            caplog.set_level(logging.WARNING, logger=logger.name)
+            logger.warning('message')
+            assert caplog.handler.level == logging.WARNING
+            assert [record.levelno for record in caplog.records] == [logging.WARNING]
+
+        def test_handler_level_after_logger_override(caplog):
+            assert caplog.handler.level == logging.NOTSET
+        """
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=2)
+
+
+def test_caplog_nested_set_level_restores_handler(testdir):
+    testdir.makepyfile(
+        """
+        import logging
+
+        def test_nested_set_level(caplog):
+            caplog.set_level(logging.INFO)
+            caplog.set_level(logging.DEBUG)
+            with caplog.at_level(logging.WARNING):
+                logging.getLogger().warning('inside')
+            assert caplog.handler.level == logging.DEBUG
+
+        def test_handler_level_after_nested_set_level(caplog):
+            assert caplog.handler.level == logging.NOTSET
+        """
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=2)
+
+
+def test_caplog_fixture_setup_level_reaches_test_body(testdir):
+    testdir.makepyfile(
+        """
+        import logging
+        import pytest
+
+
+        @pytest.fixture
+        def info_level(caplog):
+            caplog.set_level(logging.INFO)
+
+
+        def test_uses_fixture_level(caplog, info_level):
+            logger = logging.getLogger()
+            logger.debug('hidden debug message')
+            logger.info('visible info message')
+            assert caplog.handler.level == logging.INFO
+            assert [record.levelno for record in caplog.records] == [logging.INFO]
+            assert 'hidden debug message' not in caplog.text
+            assert 'visible info message' in caplog.text
+
+
+        def test_handler_level_restored_after_fixture(caplog):
+            assert caplog.handler.level == logging.NOTSET
+        """
+    )
+
+    result = testdir.runpytest()
+    result.assert_outcomes(passed=2)
+
+
 def test_log_report_captures_according_to_config_option_upon_failure(testdir):
     """ Test that upon failure:
     (1) `caplog` succeeded to capture the DEBUG message and assert on it => No `Exception` is raised