node-fs-extra fork with Pythagora tests

If you want to try it out yourself, just clone the repo and run:

npm i
npx jest ./pythagora_tests/

Bugs that Pythagora tests caught:

Edge cases

1. areIdentical returns undefined instead of false if destStat is empty object:

    test('should return false if destStat is missing ino and/or dev properties', () => {
      const srcStat = fs.statSync(__filename);
      const destStat = {};
      const result = areIdentical(srcStat, destStat);
      expect(result).toBe(false);
   });

2. isSrcSubdir says /test/src is subfolder of itself:

   test('should return false if dest is the same as src', () => {
     expect(isSrcSubdir('/test/src', '/test/src')).toBe(false);
   });