I know how this can be done!
Karma’s terminal output comes from objects called Reporters. Karma ships with some built-in Reporters (they can be found in karma/lib/reporters). Karma is also able to use custom Reporters.
You can specify which reporters are used in your project’s karma.config.js file.
For example, the ‘dots’ reporter just prints a dot when each test passes:
reporters: ['dots'],
The ‘progress’ reporter prints more than dots:
reporters: ['progress'],
The custom reporter karma-spec-reporter prints the name of each test when the test succeeds or fails (but not much else):
reporters: ['spec'],
You may want to roll your own reporter, since karma-junit-reporter, karma-spec-reporter, and the included reporters may not meet your needs.
I am guessing that customizing karma-spec-reporter is the best option in this case, since it already prints a line when a test succeeds.
If you are looking for something even more simple to work from, here is a custom reporter that I built. It reports passing and failing tests with no terminal colors.