Note why we can't write an automated test for the code path that brings up the REPL...

diff --git a/Lib/test/test_cmd_line_script.py b/Lib/test/test_cmd_line_script.py
index a08cabd2cb3aed0f12d218dcc3f8793769877b07..849abe24772e31e2ded10fd19ad88c827426bb38 100644 (file)
--- a/Lib/test/test_cmd_line_script.py
+++ b/Lib/test/test_cmd_line_script.py
@@ -143,6 +143,9 @@ class CmdLineTest(unittest.TestCase):
         self.assertIn(expected, out)
 
     def test_stdin_loader(self):
+        # Unfortunately, there's no way to automatically test the fully
+        # interactive REPL, since that code path only gets executed when
+        # stdin in an interactive tty.
         p = spawn_python()
         try:
             p.stdin.write(b"print(__loader__)\n")