Reliability testing refers to running an application to find and remove failures before deploying the system. Because there are so many different combinations of alternative paths through an application, it is impossible to find all potential failures in a complex application. However, you can test the most likely scenario under normal use, and then verify that the application provides the expected service. If time permits, more complex tests can be employed to reveal more subtle defects.
Stress reliability testing involves simulating a huge workload to see how an application performs under peak usage. With component stress testing, you can isolate constituent components and services, infer the navigation methods, functional methods, and interface methods they expose, and create test frontends that invoke these methods. For those that go into a database server or some other component, create a backend that provides dummy data in the desired format. The test instrument repeatedly inserts dummy data while observing the results.
After each individual component has been stress tested, the entire application with all its components and supporting services should be stress tested. Centralized stress testing focuses on interactions with other services, processes, and data structures (from internal components and other external application services). Centralized testing starts with the most basic functional testing. You need to know coding paths and user scenarios, understand what users are trying to do, and identify all the ways in which users use your application. The test script should run the application according to the intended usage.
Software that is reliable in an isolated, protected test environment may not be reliable in a real-world deployment. While isolation testing is useful early in the reliability testing process, a real-world test environment ensures that parallel applications do not interfere with each other. Such testing often uncovers unexpected interactions with other applications that cause failures.
It needs to be ensured that the application can run in a real environment, that is, in a server space with all expected customer event profiles, with final configuration conditions. The test plan should include running the application in the final target environment or in an environment as close as possible to the target environment. This is usually done by partially duplicating the final environment or carefully sharing the final environment.
One of the easiest ways to test reliability is to use random inputs. This type of test strives to cause the application to fail or hang by providing spurious illogical inputs. Input can be keyboard or mouse events, program message flow, Web pages, data caches, or any other input situation that can be forced into an application. Reliability testing methods of random destruction testing should be used to test significant error paths and expose bugs in the software. Such tests improve code quality by forcing failures so that returned error handling can be observed. Random testing intentionally ignores any specification of a program's behavior. If the application breaks, it fails the test. If the application does not break, the test passes. The point here is that random testing is highly automated because it doesn't care at all about how the underlying application should work.