next.js/examples/with-jest-typescript/.babelrc

{
  "env": {
    "development": {
      "presets": [
        "next/babel",
        "@zeit/next-typescript/babel"
      ]
    },
    "production": {
      "presets": [
        "next/babel",
        "@zeit/next-typescript/babel"
      ]
    },
    "test": {
      "presets": [
        [
          "next/babel",
          {
            "preset-env": {
              "modules": "commonjs"
            }
          }
        ],
        "@zeit/next-typescript/babel"
      ]
    }
  }
}