Replacing import { h } with React doesn't work in jest tests

Steps to reproduce:

1. $ preact create default preact (preact-cli v2.2.1) cd ./preact
2. npm i -D @babel/plugin-transform-react-jsx
3. Update package.json

"jest": {
    ...
    "moduleNameMapper": {
      "react": "preact/compat",
      "react-dom/test-utils": "preact/test-utils",
      "react-dom": "preact/compat"
    }
  }

1. in header.test.js replace import { h } from 'preact' with import React from 'react'
2. in .babelrc add

plugins: [
        ['@babel/plugin-transform-react-jsx', {
          "pragma": "h",
          "pragmaFrag": "Fragment"
        }]
      ]

FAIL tests/header.test.js ● Test suite failed to run

TypeError: Cannot read property 'prototype' of undefined

  3 | 
  4 | configure({
> 5 | 	adapter: new Adapter()
    | 	                                                    ^
  6 | });
  7 | 

  at node_modules/preact/compat/dist/compat.js:1:469
  at Object.<anonymous> (node_modules/preact/compat/dist/compat.js:1:611)
  at Object.<anonymous> (tests/__mocks__/setupTests.js:5:55)

[ka2n]

Changing moduleNameMapper key to regexp form will fix this issue (At least in my case).

  moduleNameMapper: {
    "^react$": "preact/compat",
    "^react-dom$": "preact/compat",
    "^react-dom/test-utils$": "preact/test-utils",
  },

background:

I ran a jest test with the Chrome Remote Debugger and found that require ('preact') in preact/compat only returned a empty object({}). Then preact/compat try to extend require('preact').Component, but it’s undefined in this situation.

[alxclark]

@ka2n Had the same issue than mentionned by @ssuvorov and it worked for me as well! 🙏