react-testing-library why is toBeInTheDocument() not a function

When you do npm i @testing-library/react make sure there is a setupTests.js file with the following statement in it

import '@testing-library/jest-dom/extend-expect';

As mentioned by Giorgio, you need to install jest-dom. Here is what worked for me:

(I was using typescript)

npm i --save-dev @testing-library/jest-dom

Then add an import to your setupTests.ts

import '@testing-library/jest-dom/extend-expect';

Then in your jest.config.js you can load it via:

"setupFilesAfterEnv": [
    "<rootDir>/src/setupTests.ts"
  ]

toBeInTheDocument is not part of RTL. You need to install jest-dom to enable it.

And then import it in your test files by: import '@testing-library/jest-dom'

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