git clone https://github.com/rails/rails/
cd rails/activesupport
bundle install
bin/test test/multibyte_chars_test.rb -n test_should_compute_grapheme_length

% bin/test test/multibyte_chars_test.rb -n test_should_compute_grapheme_length
Running 90 tests in parallel using 10 processes
Run options: -n test_should_compute_grapheme_length --seed 52859

# Running:

F

Failure:
MultibyteCharsExtrasTest#test_should_compute_grapheme_length [test/multibyte_chars_test.rb:512]:
"त्र".
Expected: 2
  Actual: 1


bin/test test/multibyte_chars_test.rb:595



Finished in 0.209643s, 4.7700 runs/s, 38.1601 assertions/s.
1 runs, 8 assertions, 1 failures, 0 errors, 0 skips
%