tests-with-rnfs.js

// some-js-file.js
export const myFunctionToTestWithRNFS = (fs) => {
  fs.readDir(...);
};
             
// some-file-when-use-rnfs.js
import RNFS from 'react-native-fs';
import { myFunctionToTestWithRNFS } from './some-js-file.js';
 
myFunctionToTestWithRNFS(RNFS);
  
// tests
import { myFunctionToTestWithRNFS } from './some-js-file.js';
  
describe('My tests', () => {
  it('should test my function with fs mock', () => {
    myFunctionToTestWithRNFS({
      readDir: () => {},
    });
  });
});