lc_integration.xml

<component name="ProjectRunConfigurationManager">
  <configuration default="false" name="lc-integration" type="mocha-javascript-test-runner" factoryName="Mocha">
    <node-options />
    <working-directory>$PROJECT_DIR$</working-directory>
    <pass-parent-env>true</pass-parent-env>
    <envs>
      <env name="NODE_ENV" value="test" />
      <env name="TZ" value="GMT" />
    </envs>
    <ui>TDD</ui>
    <extra-mocha-options>--compilers coffee:coffee-script/register --reporter spec --colors</extra-mocha-options>
    <test-directory>$PROJECT_DIR$/spec</test-directory>
    <recursive>false</recursive>
    <RunnerSettings RunnerId="RunnerForMochaJavaScript" />
    <ConfigurationWrapper RunnerId="RunnerForMochaJavaScript" />
    <method />
  </configuration>
</component>

Copy this in to the project's .idea/runConfigurations directory.

Requires JetBrains' "NodeJS" plugin.