Karma-jasmine UncaughtReference Error Statusbar not defined

I have strange occurence when testing my hybrid application build with cordova and ionic.

I use karma-jasmine for the unit-testing. If I run my test files sparately they succeed. If I run 3 of them together, they still succeed. If include all of them in karma (path/tests/*.js) 3 out of 5 succeed and following error occurs: "StatusBar" is not defined.

StatusBar is the cordova plugsin "cordova-plugin-statusbar". I wonder why it only appears when testing all files together and not one by one. I already tried to reorder the testfiles, but they always failed after the third testfile.

Everytime a test is fired, the app.js is initialized and started. I don't know if this may be a problem.

Any suggestions?