[Next.js 9.0.2] Shallow rendering issue: App cannot be invoked without 'new'

Bug report

Describe the bug

After updating our app from Next.js 7.0.2 to 9.0.2 enzyme’s shallow rendering (same issue with enzyme’s mount) for the custom <App> (_app.is) not working anymore. The local development server is serving the app perfectly fine, though.

For experimental purposes we also tried running our tests with Next.js 8.1.0 and the rendering caused no problems.

To Reproduce

Clone the issue repository: https://github.com/rzschoch/next-9-issues/tree/shallow-issue

1. Run npm install
2. Run npm run test
3. See error: TypeError: Class constructor App cannot be invoked without 'new'

Expected behavior

The test in /src/pagesSpecs/_app.spec.js should be rendered without issues and compared against the existing snapshot (from Next.js 7.0.2).

Screenshots

System information

• OS: MacOS 10.14.5 / Windows 10.0.17763 Build 17763
• Version of Next.js: 9.0.2

[dannypk]

Never mind, removing "@babel/preset-env" from "presets" solve this issue.

after i removed the preset-env in presets, all i had in .babelrc was

   "presets": [
    "next/babel"
  ] 

and it didn’t work

After that i changed to

"presets": [
    [
      "next/babel",
      {
        "preset-env": { "targets": { "node": "current" } }
      }
    ]
  ]

and it works 👍

[PaxLyj]

Never mind, removing "@babel/preset-env" from "presets" solve this issue.