Hide spurious stderr output in notebook_cmd_test.py

Author: user202729

src/sage/cli/notebook_cmd_test.py

@@ -1,3 +1,5 @@
+import io
+import sys
 import argparse
 
 import pytest
@@ -29,8 +31,14 @@ def test_jupyterlab_explicitly():
 def test_invalid_notebook_choice():
     parser = argparse.ArgumentParser()
     JupyterNotebookCmd.extend_parser(parser)
-    with pytest.raises(SystemExit):
-        parser.parse_args(["--notebook", "invalid"])
+    with io.StringIO() as f:
+        old_sys_stderr = sys.stderr
+        try:
+            sys.stderr = f
+            with pytest.raises(SystemExit):
+                parser.parse_args(["--notebook", "invalid"])
+        finally:
+            sys.stderr = old_sys_stderr
 
 
 def test_help():