“No amount of testing can prove a software right; a single test can prove a software wrong.” – Amir Ghahrai

In today's fast-paced online world, effective software testing has become a critical part of the systems development life cycle. Customers need their software implemented and updated faster than their competitors. They also need new features implemented in a very short time-frame; however, these features need to be bug-free. Thus, the available time to design, code, and test existing and new features is very limited, and it is easy for bugs to slip through into the official software releases.

Traditionally, the faster software is deployed, the less time there is to test comprehensively; ergo, the problem of bugs or errors is compounded as multiple bugs continue to be included in new software releases. This, in turn, affects the software's usability and the user experience. A negative user experience translates into a bad reputation for the software brand; therefore, the brand will lose loyal supporters and sales. In essence, it will be remembered as a bad quality product, rather than a product with a few bugs to iron out.

The five stages of Software testing

Therefore, the importance of ensuring that all software is properly tested before it is implemented cannot be overemphasised. Additionally, there are two types of software testing: automated testing or text manual testing. The differences between these two types of testing are not relevant in this context, as both of these models include the five official stages of software testing.

Therefore, let’s have a look at each of the five software testing stages:

Unit testing

Software applications are traditionally divided up into different components or units. These divisions make it simpler to code, test and deploy an application instead of having to deal with a large, unwieldy piece of software that is not broken down into core elements. Thus, the first stage of testing is known as unit testing as each component or core part is tested separately to make sure it functions as per the design specification document.

Module testing

Unit testing and module testing perform similar, albeit different functions. And, core elements are made up of modules which, in turn, encompass methods, functions, and procedures. The second stage is to test that each module’s functionality is accurate, and it is returning the desired results.

Subsystem testing

Subsystems are made up of a number of related units and modules which all interact with each other. Once all the units and modules have been successfully tested, the next step is to ensure that they function together as a subsystem. One of the most common problems in software design is the failure of subsystem elements to cooperate with each other.

System testing

This stage speaks for itself and is the final phase of the software developer’s role in the testing life cycle. In essence, systems are comprised of different subsystems to make one whole application. Again, the most common problem is to make sure that all of the various subsystems interface correctly with each other.

User acceptance testing

Once the software application has been completely developed and before it is deployed, the system is ready to be handed over to the users for testing. User acceptance testing’s primary role is to ensure that the system functions as per the business and user specification. This is also the first time where the system is tested using live or actual data.

Final words

Once these five stages of testing have been successfully completed, the software is ready to be used operationally. While this testing model is not 100% fool proof, it goes a long way towards ensuring bug-free software application deployment.