Composition provides a lightweight and generic API, that you can use to check your environment at runtime, instead of manually go checking for regex in constants, classes/functions existence, matching a version against a class constant, ...

It only works when using Composer as package management tool.

A single command to check your PHP environment :

if (!\Composition::has('vendor/super-package', '>=2.0') {
    $this->markTestSkipped('The following tests require "SuperPackage" to be at least at 2.0');
}

\Composition::has('php', '5.4.*');
\Composition::has('ext-mongo');

Check the platform :

if (\Composition::isWindows()) {
// ...
}

This tool should mostly be used in your unit tests, and not be abused in production.