reduce diff

Author: MarcoGorelli

pandas/tests/groupby/test_function.py

@@ -717,7 +717,8 @@ def test_max_nan_bug():
 -05-06,2013-05-06 00:00:00,,log.log
 -05-07,2013-05-07 00:00:00,OE,xlsx"""
 
-    df = pd.read_csv(StringIO(raw), parse_dates=[1])
+    with tm.assert_produces_warning(UserWarning, match="Could not infer format"):
+        df = pd.read_csv(StringIO(raw), parse_dates=[0])
     gb = df.groupby("Date")
     r = gb[["File"]].max()
     e = gb["File"].max().to_frame()