Add support for Jest

[akd-io]

Add support for Jest

Remember to look at this code from the github actions plugin:

scripts: [
  {
    // TODO: When testing libraries are supported, make them add the test script. Somehow make this plugin only add `test` script if no other testing plugin has done so. Currently added so the github-actions workflow won't fail when calling the `test` npm script.
    name: "test",
    description: "Runs tests",
    command: "echo No tests found.",
  },
],

[akd-io]

Check out https://nextjs.org/docs/pages/building-your-application/optimizing/testing as Lee mentioned