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A Comprehensive Guide to Testing Methodologies

Testing methodologies are the strategies, approaches and testing types used to test a particular product to ensure it is fit for purpose. They help software developers to ensure their software can operate consistently across a range of platforms and in different environments. The purpose of each testing methodology is to improve the overall quality of the software for the end-user by finding out errors and bugs within the software.

Software testing is one of the most important parts of the development process this includes functional and non-functional testing/methodologies.

Functional testing covers functionality which verifies that each function of the software application operates in conformance with the requirement specification. While, non-functional testing evaluates a wide range of other factors such as performance, usability, reliability, etc. of a software application.

Difference between Functional Testing and Non-Functional Testing

Functional Testing

- Focus on customer’s requirements.

- Helps to validate the behavior of the application.

- It describes what the product does. For Example - Check login functionality.

- Few Examples of Functional Testing Types:

  • Unit Testing - The purpose of unit testing is to allow individual parts of the software to be tested, rather than focusing on the performance of the software as a whole.

  • User Acceptance - This involves testing the final software product to make sure it complies with all business requirements and meets the needs of the end-user while performing the way that is expected. The primary purpose of acceptance testing is to determine whether the final software product is ready for delivery to the end-user.

  • Integration Testing - Integration testing occurs after each individual unit has been successfully tested. Integration testing involves taking the individual units that have been successfully tested and, then, ensuring those units work together as expected.

Non-Functional Testing

- Focus on customer’s expectation.

- Helps to validate the performance of the application.

- It describes how the product works. For Example - The dashboard should load in 2 seconds.

- Few Examples of Non-functional Testing Types

  • Performance Testing - The primary purpose of this testing is to ensure the system performs well in various scenarios that could impact a user's experience. There are several different types of performance testing, including load testing, endurance testing, spike testing and stress testing.

  • Usability Testing - The primary purpose of testing is to make sure the software's interface and design are easy to use without causing frustration or confusion. Usability testing examines a system's efficiency, memorability, learnability, errors and satisfaction.

  • Security Testing - Security testing, also known as “vulnerability testing,” involves testing software for holes in its security and vulnerabilities that could make it susceptible to hackers. The primary purpose of testing is to ensure there are no security risks within the software that could potentially expose the end-user's personal information or data.

Since Software Testing is an integral part of any Development Methodology, many companies use the term Development Methodologies & Testing Methodologies colloquially. Hence Testing Methodologies could also refer to Waterfall, Agile and other QA models.

Waterfall Model

Waterfall model is an example of a Sequential model. In this model, the software development activity is divided into different phases and each phase consists of a series of tasks and has different objectives.

The output of one phase becomes the input of the next phase. It is mandatory for a phase to be completed before the next phase starts. In short, there is no overlapping in the Waterfall model.

Figure - Waterfall Model

Testing Approach - The first phase in the waterfall model is the requirements phase in which all the project requirements are completely defined before starting the testing. During this phase, the test team brainstorms the scope of testing, test strategy and drafts a detailed test plan.

Only once the design of software is complete, the team will move on to execution of the test cases to ensure that the developed software behaves as it expected.

In this methodology, the testing team proceeds to the next phase only when the previous phase is completed.

Iterative Model

In the iterative model, developers create basic versions of the software, review and improve on the application in iterations—small steps. This is a good approach for extremely large applications that need to be completed quickly. Defects can be detected earlier, which means they can be less costly to resolve. To summarize the iterative development model is a method for breaking down any major software development project into smaller chunks. It is specifically designed to start with the bare minimum requirements and only construct a portion of the program iteratively.

Testing Approach - As soon as iteration is completed, the entire system is subjected to testing. Feedback from testing is immediately available and is incorporated in the next cycle. The testing time required in successive iteration can be reduced based on the experience gained from past iterations.

Agile Methodology

Traditional software development methodologies work on the premise that software requirements remain constant throughout the project. But with an increase in complexity, the requirements undergo numerous changes and continuously evolve. At times, the customer himself is not sure what he wants. Though the iterative model addresses this issue, it’s still based on the waterfall model.

In Agile methodology, software is developed in incremental, rapid cycles. Interactions amongst customers, developers and client are emphasized rather than processes and tools. The agile methodology focuses on responding to change rather than extensive planning.

Agile is one of the most famous project management frameworks in software development. Agile software testing is a methodology that helps developers test their code continuously and rapidly. This methodology also allows testers to get immediate feedback from customers.

Testing Approach - Incremental testing is used in agile development methods and hence, every release of the project is tested thoroughly. This ensures that any bugs in the system are fixed before the next release.

Figure – Agile Process

Which Software Methodology to choose?

There are tons of methodologies available for software development and its corresponding testing. Each testing technique and methodology is designed for a specific purpose and has its relative merits and demerits.

Selection of a particular methodology depends on many factors such as the nature of a project, client requirement, project schedule, etc.

From a testing perspective, some methodologies push for testing input early in the development life cycle, while others wait until a working model of the system is ready. This method of testing is continuous, starting at the beginning of a project and adopted as a way of working alongside an agile development approach.

Agile testing not only facilitates the early detection of defects but also reduces the cost of bugs by fixing them early. This approach also yields a customer-centric approach by delivering a high-quality product as early as possible.

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