dcomponent uses Intern as its testing setup. To run the tests, you need to install a local selenium server. You can also use Sauce Labs or something similar, but therefore you need to modify the tests/intern.js configuration. How to do this can be obtained from the Intern wiki.
Install dependencies for testing.
npm install
Install and start a selenium standalone server.
npm install selenium-standalone@latest -g
selenium-standalone install
selenium-standalone start
Run the tests.
npm test