All files related to testing should be places inside the related project source in the testing directory.
Test scripts file names should all use the template test-<project>.sh and be lower case.
When using run_tests() all those tests should be placed inside a directory named test.d inside the testing directory.
Test scripts file names when using run_tests() must be called test.sh and placed in a directory inside the test.d and that directory should have an appropriated name regarding the test:
Here are some test examples and/or templates.