JEST Global Variable isn't updated as expected

Question

When I try with the following code

script.js

var aMyVar = [];

[...]

async function load(bHard){     
    console.log(aMyVar);    
    [...]
}

[...]

module.exports = {  
    load
}    

script.test.js

const {
    load
} = require('../script.js');

[...]

describe('My Block', function () {
    test('My Test', async () => {
        global.aMyVar = [{"Key":"Test"}];
        await load(true);  
        [...]
    });
});
[...]

Expected behaviour: console.log prints "[{"Key":"Test"}]"

Observed behaviour: console.log prints "[]"

What's wrong?

Answer 1

You can use rewire package to modify the variables declared in the module scope.

Eg

script.js :

var aMyVar = [];

async function load(bHard) {
  console.log(aMyVar);
}

module.exports = { load };

script.test.js :

const rewire = require('rewire');
const mod = rewire('./script');

describe('My Block', function() {
  test('My Test', async () => {
    mod.__set__('aMyVar', [{ Key: 'Test' }]);
    await mod.load(true);
  });
});

unit test result:

 PASS  src/stackoverflow/63676669/script.test.js
  My Block
    ✓ My Test (7ms)

[ { Key: 'Test' } ]
Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        3.842s, estimated 10s