CLN/CI: Catch that stderr-warning! (pandas-dev#23706)

pandas/tests/io/parser/python_parser_only.py

@@ -8,6 +8,7 @@
 """
 
 import csv
+import sys
 
 import pytest
 
@@ -230,6 +231,7 @@ def test_multi_char_sep_quotes(self):
                 self.read_csv(StringIO(data), sep=',,',
                               quoting=csv.QUOTE_NONE)
 
+    @tm.capture_stderr
     def test_none_delimiter(self):
         # see gh-13374 and gh-17465
 
@@ -247,6 +249,9 @@ def test_none_delimiter(self):
                                warn_bad_lines=True)
         tm.assert_frame_equal(result, expected)
 
+        warning = sys.stderr.getvalue()
+        assert 'Skipping line 3' in warning
+
     def test_skipfooter_bad_row(self):
         # see gh-13879
         # see gh-15910