Cannot set property of undefined when import promise in vue component

Question

• "vue-electron": "^1.0.6"
• "electron": "4.2.4"
• "webpack": "^4.15.1"
• "vue": "^2.5.16"

In a vue component, I import a js file

<template>
...
</template>

<script>
import something from './../js/file.js';

export default {
    name: 'test',
    data() {
        return {
        };
    },
    components: {
    },
    methods: {
    },
    mounted: function() {
    }
};
</script>

In js file, I have a promise

// file.js

'use strict';

function getTest() {    
    return new Promise((resolve, reject) => {
        resolve('test')
    })
}

module.exports.getTest = getTest

And so, I have an issue : Cannot set property 'getTest' of undefined Somebody have an idea ? tks