reusable terratest code within terraform modules

[tbugfinder]

Hello,

I'm wondering how best to create re-usable terratest code for terraform modules.

I'm thinking about to add terratest test cases to terraform modules like, e.g.
https://github.com/terraform-aws-modules/terraform-aws-ec2-instance
Those tests should be sufficiently generic to cover varying variables and conditions.

Now I'm using that terraform module in my "terraform stack".
Which options are available to just call the test-cases of the module itself without copying those to the "stack" itself?

Thank You!