If you are testing a system for a corporate environment, it’s a good idea to have a dedicated suite of test machines. As a result, machines are available for end users to try out the new system without being an inconvenience to you, and they can also focus on the task at hand by being away from their own work environment. More important, it means that you are not running the software on a machine that might contain other versions of the system (or at least some of its components) that you are developing.
The nature, size, and variety of the test environment will inevitably depend on the size of your organization. A large corporation will conceivably have dedicated test rooms containing a dozen or so test machines, which will not only offer the scope to test the software under different conditions but will also allow for a degree of volume testing (several different users using the same network resources at the same time, particularly if you have developed a product that accesses a shared database). If you work for a small software house or you are an independent developer, chances are you will not be able to provide yourself with many testing resources.
Most software these days will have one of two target markets. The software will either be intended for some form of corporate environment or for commercial sale. Corporate environments can normally provide test environments, and if you work for a small software house or you are an independent developer, you will probably be expected to perform system testing on site anyway. (Obviously your user-acceptance tests must be on site.) If, however, there is no mention of this during your early contract negotiations or project planning, it is worth asking what sort of test facilities your employer or client will be able to provide for you. It’s better to arrange this at the outset rather than muddle your way through a limited test.