libxmljs doesn't work properly under Jest

[frei-0xff]

🐛 Bug Report

libxmljs package doesn't work properly when used in Jest test

To Reproduce

Try to run test:

const libxmljs = require('libxmljs')

test('Test libxmljs', () => {
  expect(
    libxmljs
      .parseXml('<customer></customer>')
      .get('/customer')
      .type()
  ).toBe('element')
})

Expected behavior

It's expected to pass, but It's failing with error:

TypeError: libxmljs.parseXml(...).get(...).type is not a function

The same code run by node.js works just fine and returns 'element'

Link to repl or repo

Minimal repository to reproduce bug: https://github.com/frei-0xff/jest-libxmljs-issue

Run npx envinfo --preset jest

  System:
    OS: Windows 10
    CPU: (2) ia32 Intel(R) Core(TM)2 Duo CPU     T7250  @ 2.00GHz
  Binaries:
    Node: 10.15.3 - C:\Program Files\nodejs\node.EXE
    npm: 5.10.0 - C:\Program Files\nodejs\npm.CMD

[frei-0xff]

As far as I managed to investigate the problem, it comes down to this:
In the following code from libxmljs module this.find is native C++ function which returns Array object

Element.prototype.get = function() {
    var res = this.find.apply(this, arguments);
    if (res instanceof Array) {
        return res[0];
    } else {
        return res;
    }
};

It returns the same Array object when executed by node.js or within jest test,
but operator

res instanceof Array

when executed by bare node.js returns true as it should,
while when executed under jest for some miraculous reason it returns false.

[jeysal]

Based on your comment about instanceof Array, it's probably caused by #2549

[frei-0xff]

Yeah, it's definitely caused by #2549
Duplicate issue. Closing.

[github-actions]

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