Running terratest

Hey,

Wondering if there's a reason why this repo doesn't supply a hook for running tests written with terratest (perhaps by default expecting to run `go test` from an expected `test/` subdirectory)?

Sorta like:
```
- id: terratest
name: terratest
description: "Run terratest unit tests"
entry: sh -c "cd test; go test -count=1 -timeout 30m -tags=unit"
language: system
files: '\.tf$'
pass_filenames: false
```

Thanks!