docker and colors reproduction

docker-compose.yml

test_runner:
    build: .
    command: npm run test-dashboard
    volumes:
        - .:/usr/src/app
    environment:
      LANG: en_US.UTF-8
      FORCE_COLOR: 'true'

docker-compose_colors.yml

test_runner:
    build: .
    command: npm run test
    volumes:
        - .:/usr/src/app
    environment:
      LANG: en_US.UTF-8
      FORCE_COLOR: 'true'

Dockerfile

FROM node:6.6

# add node modules folder to path and set global node path
ENV NODE_PATH /opt/node_modules
ENV PATH /opt/node_modules/.bin:$PATH

# copy dependency file for npm into the container --> everytime (to update possible dependencies)
ADD package.json /opt/package.json

# rm old node_modules
RUN rm -rf /opt/node_modules

# locally install project dependencies int NODE_PATH (defined above)
RUN cd /opt && npm install

WORKDIR /usr/src/app

package.json

{
    "scripts": {
        "test-dashboard": "nodejs-dashboard mocha test.js",
        "test": "mocha test.js"
    },
    "dependencies": {
        "mocha": "^3.0.2",
        "nodejs-dashboard": "^0.1.0"
    }
}

test.js

describe('test',() => {
    it('test', () => {
        throw new Error('oh hai');
    });
});