--- a/light9/run_local.py	Fri May 19 14:38:56 2023 -0700
+++ b/light9/run_local.py	Fri May 19 14:40:13 2023 -0700
@@ -38,21 +38,24 @@
 log.name = progName  # but we can rename it for clarity
 
 
-class FractionTimeFilter(logging.Filter):
+def fracTimeLogger():
+    class FractionTimeFilter(logging.Filter):
 
-    def filter(self, record):
-        record.fractionTime = (
-            time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(record.created)) +
-            ("%.3f" % (record.created % 1)).lstrip('0'))
-        # Don't filter the record.
-        return 1
+        def filter(self, record):
+            record.fractionTime = (
+                time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(record.created)) +
+                ("%.3f" % (record.created % 1)).lstrip('0'))
+            # Don't filter the record.
+            return 1
 
+    coloredlogs.install(
+        level='DEBUG',
+        fmt='%(fractionTime)s %(name)s[%(process)d] %(levelname)s %(message)s')
+    logging.getLogger().handlers[0].addFilter(FractionTimeFilter())
 
-coloredlogs.install(
-    level='DEBUG',
-    fmt='%(fractionTime)s %(name)s[%(process)d] %(levelname)s %(message)s')
-logging.getLogger().handlers[0].addFilter(FractionTimeFilter())
-
+# pytest's log replacement would try to use our fmt with fractionTime but not our handler that supports it. See https://github.com/pytest-dev/pytest/issues/2987
+if 'pytest' not in sys.modules:
+    fracTimeLogger()
 
 def setTerminalTitle(s):
     if os.environ.get('TERM', '') in ['xterm', 'rxvt', 'rxvt-unicode-256color']: