tests/silenttestrunner.py

formating: upgrade to black 20.8b1

This required a couple of small tweaks to un-confuse black, but now it
works. Big formatting changes come from:

 * Dramatically improved collection-splitting logic upstream
 * Black having a strong (correct IMO) opinion that """ is better than '''

Differential Revision: https://phab.mercurial-scm.org/D9430

from __future__ import absolute_import, print_function
import os
import sys
import unittest


def main(modulename):
    '''run the tests found in module, printing nothing when all tests pass'''
    module = sys.modules[modulename]
    suite = unittest.defaultTestLoader.loadTestsFromModule(module)
    results = unittest.TestResult()
    suite.run(results)
    if results.errors or results.failures:
        for tc, exc in results.errors:
            print('ERROR:', tc)
            print()
            sys.stdout.write(exc)
        for tc, exc in results.failures:
            print('FAIL:', tc)
            print()
            sys.stdout.write(exc)
        sys.exit(1)


if os.environ.get('SILENT_BE_NOISY'):
    main = unittest.main