Class System: A mixin constructor

[Dumas]

Hello,

how can I have a mixin constructor to augment the class instance?

This does not work:

Ext.define('MyApp.mixin.Test', {
    extend: 'Ext.mixin.Mixin',
    constructor: function(config) {
        console.info('mixin constructor called');
        this.initConfig(config);
    }
});

Ext.define('MyApp.TestClass', {
    mixins: ['MyApp.mixin.Test'],
    constructor: function(config) {
        console.info('test class constructor called');
        this.initConfig(config);
    }
});

Ext.create('MyApp.TestClass'); 

Thanks,
Roland