Method test_lost_io_open

Lib/test/test_traceback.py:531–555

(self)

    @cpython_only
    def test_lost_io_open(self):
        # GH-142737: Display the traceback even if io.open is lost
        crasher = textwrap.dedent("""\
            import io
            import traceback
            # Trigger fallback mode
            traceback._print_exception_bltin = None
            del io.open
            raise RuntimeError("should not crash")
        """)

        # Create a temporary script to exercise _Py_FindSourceFile
        with temp_dir() as script_dir:
            script = make_script(
                script_dir=script_dir,
                script_basename='tb_test_no_io_open',
                source=crasher)
            rc, stdout, stderr = assert_python_failure(script)

        self.assertEqual(rc, 1)  # Make sure it's not a crash

        expected = [b'Traceback (most recent call last):',
                    f'  File "{script}", line 6, in <module>'.encode(),
                    b'RuntimeError: should not crash']
        self.assertEqual(stderr.splitlines(), expected)

    def test_print_exception(self):
        output = StringIO()