PHPUnit_MockObject is the default mock object library for PHPUnit.

• PHP 5.6 is required but using the latest version of PHP is highly recommended

To add PHPUnit_MockObject as a local, per-project dependency to your project, simply add a dependency on phpunit/phpunit-mock-objects to your project's composer.json file. Here is a minimal example of a composer.json file that just defines a dependency on PHPUnit_MockObject 3.1:

{
    "require": {
        "phpunit/phpunit-mock-objects": "~3.1"
    }
}