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# Fail Fast Testing **(PREMIUM)**
> [Introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/198550) in GitLab 13.1.
For applications that use RSpec for running tests, we've introduced the `Verify/Failfast`
[template to run subsets of your test suite](https://gitlab.com/gitlab-org/gitlab/-/tree/master/lib/gitlab/ci/templates/Verify/FailFast.gitlab-ci.yml),
based on the changes in your merge request.
The template uses the [test_file_finder (`tff`) gem](https://gitlab.com/gitlab-org/ci-cd/test_file_finder/)
that accepts a list of files as input, and returns a list of spec (test) files
that it believes to be relevant to the input files.
`tff` is designed for Ruby on Rails projects, so the `Verify/FailFast` template is
configured to run when changes to Ruby files are detected. By default, it runs in
the [`.pre` stage](../../../ci/yaml/README.md#pre-and-post) of a GitLab CI/CD pipeline,