POI 10, tests and coverage

The problem

You're using POI 10 with @poi/plugin-karma and want to get coverage of your unit tests. The way to do it is to specify:

  plugins: [
    require('@poi/plugin-karma')({
      coverage: true,
    })
  ]

and theoretically you should be all set. Only that it won't work:

TypeError: Cannot read property 'preLoaders' of undefined

I've looked everywhere and it seems that it is, unfortunately, not a known problem. What is even worse the GitHub repo with POI sources, version 10, is GONE! I mean I understand everything but removing history of an opensource project - that is a bit too much for me. SHAME ON YOU, EGOIST!

The solution

The problem is that @poi/plugin-karma taps directly to options of the vue-loader whist seems to be undefined at that point. The quick and dirty solution is to add those options:

  plugins: [
    require('@poi/plugin-karma')({
      coverage: true,
      chainWebpack (config) {
        config.module.rule('vue').use('vue-loader').options({})
      }
    })
  ]

I need to dig more into the matter why vue-loader isn't configured there and why the hell when testing a Vue.js SFC still causes errors but for now for testing just javascript code the above solution works

Happy coding