Help developing preprocessor for karma

[Tobias Timm]

Hi guys, i have a question about the karma test execution, maybe someone can give me the last needed hint. I try to implement a preprocessor using FuseBox (module-bundler like webpack). I'm transpiling the js files and give the result to karma. Karma is bootstrapping successfully and within the devtools the js files are looking fine, but unfortunately karma is saying that there are no tests.

My repo is
https://github.com/TobiasTimm/karma-fuse-box

would appreciate any help