gh-151162: Increase test coverage for string formatting

[manoj-marimuthu]

In Lib/test/test_str.py, string formatting is tested for nan and inf but not for -inf. -inf could be the most important among them (since we have to check if '-' formats correctly). The following PR adds 2 test cases for -inf with %f and %F.

Existing:

self.assertEqual('%f' % NAN, 'nan')
self.assertEqual('%F' % NAN, 'NAN')
self.assertEqual('%f' % INF, 'inf')
self.assertEqual('%F' % INF, 'INF')

Added:

self.assertEqual('%f' % -INF, '-inf')
self.assertEqual('%F' % -INF, '-INF')

• Issue: Increase test coverage for string formatting #151162

[StanFromIreland]

This is already covered in test_float.RoundTestCase.test_format_specials, and I don't think the second case is particularly special here.

[manoj-marimuthu]

Thanks for taking the time to inform. Will close it.

[bedevere-app]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.