Composer autoload in Wordpress custom plugin - php

Question

I'm developing a brand new Wordpress plugin and I would like to use Composer to autoload classes.
Here is the plugin directory heriarchy:
my composer.json content:
{
"autoload": {
"psr-4": {
"G4S_ECommerce\\": "src"
}
}
}
In the directory where composer.json is, on cmd, I execute:
composer install -> this generates the vendor/composer folder and the vendore/autoload.php.
composer composer dumpautoload -o -> outputs "Generated optimized autoload files containing 0 classes"
In the main file G4S_Ecommerce.php I put the following line:
require __DIR__.'/vendor/autoload.php';
In the same file I put
use G4S_Ecommerce\Includes\Ecommerce;
$starter = new Ecommerce();
but it leads me to a Fatal error: Uncaught Error: Class 'G4S_Ecommerce\Includes\Ecommerce' not found
Why the composer dumpautoload -o returns 0 classes? What am I doing wrong?
Thanks

Answer 1

First (it is not obvious from your files structure) you need to set a namespace for your Ecommerce class (i.e., G4S_Ecommerce/Includes)
Second, based on what you've declared in the autoload directive, composer is expecting to find the G4S_Ecommerce folder under the src folder, and in that folder you need to place your php class file with a name identical to the class name (i.e., Ecommerce).