Scalability Testing is a non-functional test methodology in which an application's performance is measured in terms of its ability to scale up or scale down the number of user requests or other such performance measure attributes. Scalability testing can be performed at a hardware, software or database level or a system's ability to grow by increasing the workload per user, or the number of concurrent users, or the size of a database.

We create repeatable test scenarios for each of the scalability testing attributes and test the application for varying levels of load such as low, medium and high loads and verify the behavior of an application. We create a test environment that is stable enough to withstand the entire scalability testing cycle and configure the hardware necessary to perform this testing. We define a set of virtual users for verifying the behavior of an application under varying user load. Repeat the test scenarios for multiple users under varying conditions of internal applications, hardware and database changes. In case of a clustered environment, validate if the load balancer is directing the user requests to multiple servers to ensure that no server is overloaded by a series of requests. We execute the test scenarios in the test environment and analyze the reports generated and verify the areas of improvement, if any.