.babelrc

{
  "env": {
    "development": {
      "presets": ["next/babel", "@zeit/next-typescript/babel"],
      "plugins": [
        ["@babel/plugin-proposal-decorators", { "legacy": true }],
        ["@babel/plugin-proposal-class-properties", { "loose": true }],
        ["styled-components", { "ssr": true, "displayName": true }]
      ]
    },
    "production": {
      "presets": ["next/babel", "@zeit/next-typescript/babel"],
      "plugins": [
        ["@babel/plugin-proposal-decorators", { "legacy": true }],
        ["@babel/plugin-proposal-class-properties", { "loose": true }],
        ["styled-components", { "ssr": true, "displayName": false }]
      ]
    },
    "test": {
      "presets": [
        [
          "next/babel",
          {
            "preset-env": {
              "modules": "commonjs"
            }
          }
        ],
        "@zeit/next-typescript/babel"
      ],
      "plugins": [
        ["@babel/plugin-proposal-decorators", { "legacy": true }],
        ["@babel/plugin-proposal-class-properties", { "loose": true }],
        ["styled-components", { "ssr": true, "displayName": false }]
      ]
    }
  }
}