logging.py: Don't change log level of the root logger to bigger numer…

…ic value

AUTHORS

@@ -105,6 +105,7 @@ Jurko Gospodnetić
 Justyna Janczyszyn
 Kale Kundert
 Katarzyna Jachim
+Katerina Koukiou
 Kevin Cox
 Kodi B. Arfer
 Lawrence Mitchell

_pytest/logging.py

@@ -153,7 +153,7 @@ def catching_logs(handler, formatter=None, level=None):
         root_logger.addHandler(handler)
     if level is not None:
         orig_level = root_logger.level
-        root_logger.setLevel(level)
+        root_logger.setLevel(min(orig_level, level))
     try:
         yield handler
     finally:

changelog/3307.feature.rst

@@ -0,0 +1,3 @@
+pytest should not change the log level of the root logger
+when the ``log-level`` parameter is set with value
+``LOG_LEVEL>root_logger_level``.

doc/en/logging.rst

@@ -224,6 +224,8 @@ made in ``3.4`` after community feedback:
 
 * Log levels are no longer changed unless explicitly requested by the :confval:`log_level` configuration
   or ``--log-level`` command-line options. This allows users to configure logger objects themselves.
+  When this parameter is used and user requests log level of smaller numeric value than the log level of the root
+  logger then the root logger will be adjusted to have level equal to the requested logging level.
 * :ref:`Live Logs <live_logs>` is now disabled by default and can be enabled setting the
   :confval:`log_cli` configuration option to ``true``. When enabled, the verbosity is increased so logging for each
   test is visible.

testing/logging/test_reporting.py

@@ -49,6 +49,27 @@ def test_foo():
                                  'text going to stderr'])
 
 
+def test_root_logger_affected(testdir):
+    testdir.makepyfile('''
+        import logging
+
+        logger = logging.getLogger()
+        logger.setLevel(logging.DEBUG)
+        logger.addHandler(logging.FileHandler('pytest.log'))
+
+        def test_foo():
+            logger.debug('debug text going to logger')
+            logger.info('info text going to logger')
+        ''')
+    log_file = testdir.tmpdir.join('pytest.log').strpath
+    result = testdir.runpytest('--log-level=INFO')
+    assert os.path.isfile(log_file)
+    with open(log_file) as rfh:
+        contents = rfh.read()
+        assert all(x in contents for x in ["debug text going to logger",
+                                           "info text going to logger"])
+
+
 def test_setup_logging(testdir):
     testdir.makepyfile('''
         import logging