Thread: Performance and Functional Testing

What is the difference between Performance and Functional Testing?Is it applicable to automation also?

Originally Posted by sumedh_autoall

What is the difference between Performance and Functional Testing?Is it applicable to automation also?

Hi Sumedh

in Performance testing Automation is important coz manualy this task is goes very tidious,

In software engineering, performance testing is testing that is performed, from one perspective, to determine how fast some aspect of a system performs under a particular workload. It can also serve to validate and verify other quality attributes of the system, such as scalability and reliability. Performance testing is a subset of Performance engineering, an emerging computer science practice which strives to build performance into the design and architecture of a system, prior to the onset of actual coding effort.

Performance testing can serve different purposes. It can demonstrate that the system meets performance criteria. It can compare two systems to find which performs better. Or it can measure what parts of the system or workload cause the system to perform badly. In the diagnostic case, software engineers use tools such as profilers to measure what parts of a device or software contribute most to the poor performance or to establish throughput levels (and thresholds) for maintained acceptable response time. It is critical to the cost performance of a new system, that performance test efforts begin at the inception of the development project and extend through to deployment. The later a performance defect is detected, the higher the cost of remediation. This is true in the case of functional testing, but even more so with performance testing, due to the end-to-end nature of its scope.

In performance testing, it is often crucial (and often difficult to arrange) for the test conditions to be similar to the expected actual use. This is, however, not entirely possible in actual practice. The reason is that production systems have a random nature of the workload and while the test workloads do their best to mimic what may happen in the production environment, it is impossible to exactly replicate this workload variability - except in the most simple system.

Loosely-coupled architectural implementations (e.g.: SOA) have created additional complexities with performance testing. Enterprise services or assets (that share common infrastructure or platform) require coordinated performance testing (with all consumers creating production-like transaction volumes and load on shared infrastructures or platforms) to truly replicate production-like states. Due to the complexity and financial and time requirements around this activity, some organizations now employ tools that can monitor and create production-like conditions (also referred as "noise") in their performance testing environments (PTE) to understand capacity and resource requirements and verify / validate quality attributes.

In Funcational Testing
users are expecting it to.

Many times the development of a system is likened to the building of a house. While this analogy isn't quite correct, we can extend it for the purposes of understanding the difference between unit and functional tests. Unit testing is analogous to a building inspector visiting a house's construction site. He is focused on the various internal systems of the house, the foundation, framing, electrical, plumbing, and so on. He ensures (tests) that the parts of the house will work correctly and safely, that is, meet the building code. Functional tests in this scenario are analogous to the homeowner visiting this same construction site. He assumes that the internal systems will behave appropriately, that the building inspector is performing his task. The homeowner is focused on what it will be like to live in this house. He is concerned with how the house looks, are the various rooms a comfortable size, does the house fit the family's needs, are the windows in a good spot to catch the morning sun. The homeowner is performing functional tests on the house. He has the user's perspective. The building inspector is performing unit tests on the house. He has the builder's perspective.

Like unit tests, writing a suite of maintainable, automated functional tests without a testing framework is virtually impossible. JUnit is very good at unit testing; however, it unravels when attempting to write functional tests. There is no equivalent of JUnit for functional testing. There are products available for this purpose, but I have never seen these products used in a production environment. If you can't find a testing framework that meets your needs, you'll have to build one.

No matter how clever we are at building the projects we work on, no matter how flexible the systems are that we build, if what we produce isn't usable, we've wasted our time. As a result, functional testing is the most important part of development.

Because both types of tests are necessary, you'll need guidelines for writing them.