How to run Karma tests from docker container?

I've found this docker image to be an excellent starting point for running karma tests quickly inside a docker container on Concourse CI:

https://hub.docker.com/r/markadams/chromium-xvfb-js/

It contains node 6.x (latest) + npm and a headless chromium instance using X virtual framebuffer. Working great for me!

There is also protractor-runner project, and Karma is similar to running Protractor, and so you might be able to learn how to do it from that example. But, I prefer the suggestion to use chromium-xvfb-js image.

Use PhantomJS instead of Chrome. Karma has PhantomJS launcher.

PhantomJS based on Blink.

Install PhantomJS:

npm karma-phantomjs-launcher --save-dev

Add to Karma config:

module.exports = function(config) {  config.set({    browsers : ['PhantomJS']  });};

EDIT

Here is part od Dockerfile

ENV NODE_VERSION 0.12.7ENV NPM_VERSION 3.5.1ENV PHANTOM_JS phantomjs-1.9.8-linux-x86_64# App and testRUN set -x \    && buildDeps='curl git bzip2 file libfreetype6 libfontconfig1 python-pip python-dev libpq-dev libmemcached-dev libzmq-dev libjpeg62-turbo-dev zlib1g-dev libtiff5-dev make g++ psmisc' \    && apt-get update \    && apt-get install -y $buildDeps --no-install-recommends \    && rm -rf /var/lib/apt/lists/* \    && curl -SLO "https://bitbucket.org/ariya/phantomjs/downloads/$PHANTOM_JS.tar.bz2" \    && tar xvjf $PHANTOM_JS.tar.bz2 \    && mv $PHANTOM_JS /usr/local/share \    && ln -sf /usr/local/share/$PHANTOM_JS/bin/phantomjs /usr/local/bin \    && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.gz" \    && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \    && gpg --verify SHASUMS256.txt.asc \    && grep " node-v$NODE_VERSION-linux-x64.tar.gz\$" SHASUMS256.txt.asc | sha256sum -c - \    && tar -xzf "node-v$NODE_VERSION-linux-x64.tar.gz" -C /usr/local --strip-components=1 \    && rm "node-v$NODE_VERSION-linux-x64.tar.gz" SHASUMS256.txt.asc \    && npm install -g npm@"$NPM_VERSION" grunt-cli \    && npm install \    && npm cache clear \    && ./node_modules/.bin/bower install --allow-root \    && npm test \    && apt-get purge -y --auto-remove $buildDeps \    && rm -rf /usr/local/bin/node /usr/local/bin/npm /usr/local/include/node /usr/local/lib/node_modules \    && rm -rf /usr/local/share/$PHANTOM_JS /usr/local/bin/phantomjs

In this case Docker made one layer. In this layer

1. install libs and tools (debian jessie)
2. install PhantomJS
3. install NodeJS
4. run tests
5. remove libs and tools
6. remove NodeJS
7. remove PhantomJS

Tests are running and You don't have PhantomJS in production container.