Method test_summary_should_show_carets

Lib/test/test_traceback.py:3493–3526

(self)

        )

    def test_summary_should_show_carets(self):
        # See: https://github.com/python/cpython/issues/122353

        # statement to execute and to get a ZeroDivisionError for a traceback
        statement = "abcdef = 1 / 0 and 2.0"
        colno = statement.index('1 / 0')
        end_colno = colno + len('1 / 0')

        # Actual line to use when rendering the traceback
        # and whose AST will be extracted (it will be empty).
        cached_line = '# this line will be used during rendering'
        self.addCleanup(unlink, TESTFN)
        with open(TESTFN, "w") as file:
            file.write(cached_line)
        linecache.updatecache(TESTFN, {})

        try:
            exec(compile(statement, TESTFN, "exec"))
        except ZeroDivisionError as exc:
            # This is the simplest way to create a StackSummary
            # whose FrameSummary items have their column offsets.
            s = traceback.TracebackException.from_exception(exc).stack
            self.assertIsInstance(s, traceback.StackSummary)
            with unittest.mock.patch.object(s, '_should_show_carets',
                                            wraps=s._should_show_carets) as ff:
                self.assertEqual(len(s), 2)
                self.assertListEqual(
                    s.format_frame_summary(s[1]).splitlines(),
                    [
                        f'  File "{TESTFN}", line 1, in <module>',
                        f'    {cached_line}'
                     ]
                )
                ff.assert_called_with(colno, end_colno, [cached_line], None)

class Unrepresentable:
    def __repr__(self) -> str: