List of karma build erorrs:

One thing that is frustrating, and recurrent engouh; karma build errors on travis.

Aborted due to warnings.
npm ERR! Test failed.  See above for more details.
npm ERR! not ok code 0

files not found:

If karma does not find your files, it will fail. For instance, I refactored my app to install bower dependency files from libs to lib and forgot to update the .bowerrc file. Thus, the files were getting installed in one directory and the karma setup was looking for them in the wrong place.

DEBUG [launcher]: /usr/local/phantomjs/bin/phantomjs /tmp/karma-37940907/capture.js
WARN [watcher]: Pattern "/home/travis/build/goliatone/gioc/lib/jquery/jquery.js" does not match any file.
WARN [watcher]: Pattern "/home/travis/build/goliatone/gioc/lib/requirejs/require.js" does not match any file.
...
Warning: Task "karma:ci" failed. Use --force to continue.