After having a lot of problems making my unit tests run and not to break my project (after fixing some npm-issues my tests did run but my app did not build for android anymore). I learned a lot of stuff: one reason for my building problems were some added hooks ( it took me some time to figure that our because the hooks directory is in .gitignore and for that reason was out of my mind too ;-)). After a lot of investigation for the reason of this log

npm ERR! enoent ENOENT: no such file or directory, rename

I found the dead simple solution: just update npm

npm update npm -g

After that tns test init worked like a charm and my test run fine (without breaking my builds).