A very simple example of Next.js-based website with Jest tests, all written in TypeScript.

$ yarn install

$ yarn test
yarn run v1.22.5
$ jest
 PASS  __tests__/index.test.tsx
  With Enzyme
    √ App shows "A simple example repo" in a <p> tag (7 ms)
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        2.893 s, estimated 4 s
Ran all test suites.
Done in 4.09s.

• package.json/jest: use ts-jest to test TypeScript files; use mocks for imported CSS/LESS files; use TypeScript compiler to handle both TS/JS files
• jest.setup.ts: use enzyme to test with jQuery-like APIs
• tsconfig.jest.json: handles JSX transformation by ts-jest during the test

https://github.com/vercel/next.js/tree/master/examples/with-typescript-eslint-jest

• does not use CSS files
• uses babel-jest instead of ts-jest

https://github.com/arcatdmz/nextjs-with-jest-typescript

• npm install issue resolved - refer - #3