Software testing is an integral part of the software development life cycle (SDLC). Effectively and efficiently testing a piece of code is equally important, if not more, than writing it. So what is software testing? Well, for those of you who are new to software testing and quality assurance, here’s the answer to this question.

Software testing is nothing but subjecting a piece of code to both, controlled as well as uncontrolled operating conditions, in an attempt to observe the output and examine whether it is in accordance with certain pre-specified conditions. Different sets of test cases and testing strategies are prepared, all of which aim at achieving one common goal – removing all the bugs and errors from the code and making the software error-free and capable enough of providing accurate and optimum outputs. There are different types of software testing techniques and methodologies. A software testing methodology is different from a software testing technique. We will have a look at a few software testing methodologies in the later part of this article.

Software Testing Methods
There are different types of testing methods or techniques as part of the software testing process. I have enlisted a few of them below.

• White box testing
• Black box testing
• Gray box testing
• Unit testing
• Integration testing
• Regression testing
• Usability testing
• Performance testing
• Scalability testing
• Software stress testing
• Recovery testing
• Security testing
• Conformance testing
• Smoke testing
• Compatibility testing
• System testing
• Alpha testing
• Beta testing

The above software testing methods can be implemented in two ways – manually or by automation. Manual software testing is done by human software testers who manually i.e. physically check, test and report errors or bugs in the product or piece of code. In case of automated software testing, the same process is performed by a computer by means of an automated testing software such as WinRunner, LoadRunner, Test Director, etc.

Software Testing Methodologies
These are some commonly used software testing methodologies:

• Waterfall model
• V model
• Spiral model
• RUP
• Agile model
• RAD

Let us have a look at each one of these methodologies one by one.

Waterfall Model
The waterfall model adopts a ‘top down’ approach regardless of whether it is being used for software development or testing. The basic steps involved in this software testing methodology are:

• Requirement analysis
• Test case design
• Test case implementation
• Testing, debugging and validating the code or product
• Deployment and maintenance

In this methodology, you move on to the next step only after you have completed the present step. There is no scope for jumping backward or forward or performing two steps simultaneously. Also, this model follows a non-iterative approach. The main benefit of this methodology is its simplistic, systematic and orthodox approach. However, it has many shortcomings since bugs and errors in the code are not discovered until and unless the testing stage is reached. This can often lead to wastage of time, money and valuable resources.

V Model
The V model gets its name from the fact that the graphical representation of the different test process activities involved in this methodology resembles the letter ‘V’. The basic steps involved in this methodology are more or less the same as those in the waterfall model. However, this model follows both a ‘top-down’ as well as a ‘bottom-up’ approach (you can visualize them forming the letter ‘V’). The benefit of this methodology is that in this case, both the development and testing activities go hand-in-hand. For example, as the development team goes about its requirement analysis activities, the testing team simultaneously begins with its acceptance testing activities. By following this approach, time delays are minimized and optimum utilization of resources is assured.

Spiral Model
As the name implies, the spiral model follows an approach in which there are a number of cycles (or spirals) of all the sequential steps of the waterfall model. Once the initial cycle is completed, a thorough analysis and review of the achieved product or output is performed. If it is not as per the specified requirements or expected standards, a second cycle follows, and so on. This methodology follows an iterative approach and is generally suited for very large projects having complex and constantly changing requirements.

Rational Unified Process (RUP)
The RUP methodology is also similar to the spiral model in the sense that the entire testing procedure is broken up into multiple cycles or processes. Each cycle consists of four phases namely; inception, elaboration, construction and transition. At the end of each cycle, the product or the output is reviewed and a further cycle (made up of the same four phases) follows if necessary. Today, you will find certain organizations and companies adopting a slightly modified version of the RUP, which goes by the name of Enterprise Unified Process (EUP).

Agile Model
This methodology follows neither a purely sequential approach nor does it follow a purely iterative approach. It is a selective mix of both of these approaches in addition to quite a few new developmental methods. Fast and incremental development is one of the key principles of this methodology. The focus is on obtaining quick, practical and visible outputs and results, rather than merely following theoretical processes. Continuous customer interaction and participation is an integral part of the entire development process.

Rapid Application Development (RAD)
The name says it all. In this case, the methodology adopts a rapid development approach by using the principle of component-based construction. After understanding the various requirements, a rapid prototype is prepared and is then compared with the expected set of output conditions and standards. Necessary changes and modifications are made after joint discussions with the customer or the development team (in the context of software testing). Though this approach does have its share of advantages, it can be unsuitable if the project is large, complex and happens to be of an extremely dynamic nature, wherein the requirements are constantly changing. Here are some more advantages of rapid application development.

This was a short overview of some commonly used software testing methodologies. With the applications of information technology growing with every passing day, the importance of proper software testing has grown multifold.