Unit test for is_causal Better Transformers (#91900) (#92102)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/91900
Test Plan:
buck test :test_transformers -- -r test_train_with_is_causal
buck test mode/opt :test_transformers -- -r test_is_causal_gpu
flake8 test_transformers.py
Differential Revision: D42453642
Pull Request resolved: https://github.com/pytorch/pytorch/pull/92102
Approved by: https://github.com/drisspg
