Thank you for making this wonderful plugin!

I've been trying to update from vue-cli-plugin-unit-karma, but there is one blocker:

The karma config in this plugin only supports a limited number of options: https://github.com/tushararora/vue-cli-plugin-unit-karmajs/blob/master/karma.conf.js#L16

If additional options are needed such as customLaunchers (http://karma-runner.github.io/4.0/config/browsers.html), they do not get merged in with the config. vue-cli-plugin-unit-karma supported custom options as shown here: https://github.com/davidwallacejackson/vue-cli-plugin-unit-karma/blob/master/karma.conf.js#L44