Jest: `TypeError: Cannot read property 'registerLocale' of undefined` about node-i18n-iso-countries

[asode]

Got around the issue by mocking the functions:

jest.mock("i18n-iso-countries", () => ({
  default: jest.fn(),
  registerLocale: jest.fn(),
  getNames: jest.fn().mockResolvedValue({ EN: "English" }),
}));

But is this really required? Shouldn't the library work with jest even without mocking?

[Gurochka]

It seems that jest can't find localization files to insert them to registerLocale. Another solution is to add a root path to the jest.config.js file:
roots: ["<rootDir>/src", "<rootDir>/node_modules/i18n-iso-countries"].
That worked for me.