How to perform unit test on SCons complex build system?

I want to perform some unit test for a SCons based build.

I want to test the methods implemented in my customized tools and also the methods implemented in the SConstruct.

So far I checked with Python module unittest .

I am stucked at the point of defining how to run/call these tests and also how to import SConstruct module.

Folder structure:

SConstruct
SConscript
source_code/
path_to_custom_tools(C:/../../)/
        tools_folder1/tool1.py
        tools_folder2/tool2.py

Any suggestions on how to perform this tests ? I also need suggestions regarding where to place this tests since the tools are located in a different location then site-scons.