Definition
Testing of those requirements that do not relate to functionality, such as performance and usability.
[Source: =BCS]
Comment
This ensures that bugs are found in all the areas where ‘business functionality’ is not of the essence. For example, where specified,performance testing, security testing and usability testing of the requirements are met. It provides confidence that the system functions in a secure, timely and useable manner and operates under likely error conditions.
It is always better to document non-functional requirements prior to the tests being executed or the results are always declared to be ‘good enough’ until the users reject the system.
Non-functional testing is also known as technical testing or technical requirements testing
On many programmes and large projects, testing will take up a significant portion of the budget. But it will receive less management attention than an activity of this size warrants.