main, logging: restore old logger settings to avoid pytest vomiting in certain situations

2 files changed, 16 insertions, 6 deletions

diff --git a/diffoscope/logging.py b/diffoscope/logging.py
index 38bb9bf..3668aa3 100644
--- a/diffoscope/logging.py
+++ b/diffoscope/logging.py
@@ -17,11 +17,14 @@
 # You should have received a copy of the GNU General Public License
 # along with diffoscope.  If not, see <https://www.gnu.org/licenses/>.
 
+import contextlib
 import logging
 
 
+@contextlib.contextmanager
 def setup_logging(debug, log_handler):
     logger = logging.getLogger()
+    oldLevel = logger.getEffectiveLevel()
     logger.setLevel(logging.DEBUG if debug else logging.WARNING)
 
     ch = log_handler or logging.StreamHandler()
@@ -33,3 +36,11 @@ def setup_logging(debug, log_handler):
         '%Y-%m-%d %H:%M:%S',
     )
     ch.setFormatter(formatter)
+    try:
+        yield logger
+    finally:
+        # restore old logging settings. this helps pytest not spew out errors
+        # like "ValueError: I/O operation on closed file", see
+        # https://github.com/pytest-dev/pytest/issues/14#issuecomment-272243656
+        logger.removeHandler(ch)
+        logger.setLevel(oldLevel)
diff --git a/diffoscope/main.py b/diffoscope/main.py
index b91f8b5..60e6600 100644
--- a/diffoscope/main.py
+++ b/diffoscope/main.py
@@ -322,11 +322,7 @@ def maybe_set_limit(config, parsed_args, key):
     elif parsed_args.no_default_limits:
         setattr(config, key, float("inf"))
 
-
-def run_diffoscope(parsed_args, post_parse):
-    log_handler = ProgressManager().setup(parsed_args)
-    setup_logging(parsed_args.debug, log_handler)
-    post_parse(parsed_args)
+def run_diffoscope(parsed_args):
     ProfileManager().setup(parsed_args)
     PresenterManager().configure(parsed_args)
     logger.debug("Starting diffoscope %s", VERSION)
@@ -394,7 +390,10 @@ def main(args=None):
         with profile('main', 'parse_args'):
             parser, post_parse = create_parser()
             parsed_args = parser.parse_args(args)
-        sys.exit(run_diffoscope(parsed_args, post_parse))
+        log_handler = ProgressManager().setup(parsed_args)
+        with setup_logging(parsed_args.debug, log_handler) as logger:
+            post_parse(parsed_args)
+            sys.exit(run_diffoscope(parsed_args))
     except KeyboardInterrupt:
         logger.info('Keyboard Interrupt')
         sys.exit(2)