How to mock the imported "package.json" in Jest?

Question

My React application refers version in the imported package.json .

import pjson from './package.json';

// snip

<p>Version: ${pjson.version}</p>

In the example above, Jest would display an error message like this:

TypeError: Cannot read properties of undefined (reading 'version')

  69 |
> 70 |     <p>Version: v{pjson.version}</p>
     |                         ^

How can I mock this up?

Answer 1

Just importing with asterisks solved the problem.
Neither mock nor moduleNameMapper is needed.

• src/App.tsx

import * as pjson from './package.json';

Answer 2

I made these files. But the same.

jest.config.ts :

const config: Config.InitialOptions = {
  moduleNameMapper: {
    '^.+\\.json$': '<rootDir>/__mocks__/mock.json',
  },
};

__mocks__/mock.json :

{
  "version": "0"
}