weback warning when running tests of generated app

[doppelreim]

Version

3.0.0-beta.11

Reproduction link

https://github.com/doppelreim/vue-test-app

Steps to reproduce

Install dependencies: npm install

Run the unit-tests: ./node_modules/.bin/vue-cli-service test:unit

What is expected?

The tests should pass without warnings.

What is actually happening?

 WEBPACK  Compiled with 1 warning(s)

Warning 

  configuration
  The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
  You can also set it to 'none' to disable any default behavior. Learn more: https://webpack.js.org/concepts/mode/

---

The repro-repo contains just a freshly generated app:
(actually generated with beta12)

Vue CLI v3.0.0-beta.12
? Please pick a preset: Manually select features
? Check the features needed for your project: TS, Router, CSS Pre-processors, Linter, Unit, E2E
? Use class-style component syntax? Yes
? Use Babel alongside TypeScript for auto-detected polyfills? No
? Pick a CSS pre-processor (PostCSS, Autoprefixer and CSS Modules are supported by default): LESS
? Pick a linter / formatter config: TSLint
? Pick additional lint features: 
? Pick a unit testing solution: Mocha
? Pick a E2E testing solution: Cypress
? Where do you prefer placing config for Babel, PostCSS, ESLint, etc.? In dedicated config files
? Save this as a preset for future projects? (y/N)

Looks like this is an issue with the configuration of webpack?