To reduce the complexity in your test scripts, it would be ideal if the test scripts are written in the same language as the software module under test. If you are writing your software module in C, your test scripts should also be written in C. If you are using rust, then rust should be used for the test scripts.
The advantage of using the same language for both the software module and test script, it is compiled for testing on the target. The big assumption is that the language is already supported by your target. In some cases, this is not. If you are developing using embedded Linux and your test scripts are in written in python, the chance of your version of python being supported on your target is pretty good. However, if you are targeting an 8bit Atmel AVR, getting python support on the target is pretty slim. If the test script is in the same language as the software module for your target, you are pretty certain that test on target is possible.
The other advantage of using the same language is the ability to debug. In a mixed language environment, the chance of debugging your test script as well as your software module is pretty small. For example, the software module is written in C and the test script is also written in C. When the binary is created and executed, it can be easily debugged using
gdbor another debugger. It can be debugged from entry into
main()until it exits
main(). The variables can also be inspected and modified during debugging quite easily. In a mixed language environment, the variables public names may be mangled and that would make it difficult to find for inspection or even to modified.
To sum up, if you have no compelling reason to not keep all of your test script and software module in the single language domain such as C, do not mix your language.
I am writing a Guide to Successful Unit Tests, you can get it here at Leanpub.