use foreach to create executables

[Jyun-Neng]

Instead of explicitly create an executable for each test, I think we can use foreach to reduce the lines.

[d99kris]

Hi @Jyun-Neng - thanks for contributing! From a quick glance this looks like a good improvement. I'll just need to take a proper good look before merging, hopefully I'll get a chance in the next week or two.