Levels of Testing in Software Testing In Agile With Examples

Software development is a collaborative process. Developers and testers work together to release a high-quality product that has been subjected to the necessary testing procedures.

Software testers use a wide variety of software testing methods to ensure that the final product is its best. Software testers use different levels of testing for various purposes, but all with a focus on quality. We will give specific detail about these levels below.

Before starting about different levels of software testing, let’s try to understand:

What is Testing?

Testing is a process of validating if the product or service under consideration meets specified requirements. The purpose of testing is to find out faults in your software before releasing it on the market since once your application enters the market you can’t go back and fix any issues that occur.

Testing is not just about finding bugs; it also encompasses verifying that the product or service under test meets its requirements, specifications, and quality standards set by the organization. Testing helps improve the quality of a software application since it verifies that all functionalities work as they should — no bugs are left unchecked.

Testing is an important part of any development process because you want to make sure that your end result is the best that it can be. It is important to note that the different types of testing are done throughout different stages of development, not just at the end.

Testing your application also gives you a chance to simulate real-life scenarios and identify any patterns or errors that may occur in those situations. This way you can fix the issues before they are released to the public.

After getting a quick knowledge on what is testing let us shift our focus towards

Whats is software testing?

Software testing is a process of validating and verifying that the software meets all the requirements that have been set for it. It includes mainly two types of activities:

Test Planning: This is the process of defining what needs to be tested in order to validate that the software meets all its requirements. It is also known as test chartering and requirement analysis.

Testing: This involves the actual execution of tests on the application with an aim of determining if it meets all its requirements or not. The outcome of this activity is known as a test log or results.

Testing also includes the process of evaluating the software after it has been released to ensure that it meets your expectations and can be used by your customers. In this article, we will focus on testing in the different stages of the software development cycle.

Test Types / Levels:

Different types of testing are performed at different stages of development. Once you understand these testing levels, you will be in a better position to decide how and when your software should be tested.

Software Testing – Levels: These are primarily three levels of software testing:

  • Unit Level Testing
  • Integration Level Testing
  • System Level Testing

We will see details about these levels in this article in detail.

Test Levels are also classified into four broad categories:

  • Black Box Testing
  • White Box Testing
  • Acceptance Testing
  • Compatibility Testing

More about each of these test types will be discussed later in the article. Let’s first look at different levels of testing and their advantages and disadvantages before getting into their detail.

Types of Testing

As we discussed above, there are different levels of testing. Each level of testing is divided into further sub-levels depending on the technique(s) used to perform the tests and validate that your application meets its requirements or not. These sub-levels within each level represent a progressive approach to ensure thoroughness when it comes to testing your application, which is why we divide software testing into different levels.

There are different types of software testing performed at different levels throughout the entire development process. These are:

  • Functional Testing
  • Non- Functional Testing (NFT)

In this article, we will focus on two main types of software testing: functional testing and non-functional testing (NFT) — also known as acceptance testing. The reason we have chosen these two types is that they are by far the most important types of testing performed at different stages in the development process and most other forms of the testing stem from these two.

Functional Testing: This is a type of software testing that is carried out on an application to ensure it functions according to its requirements. It involves validating the correct behavior of each function individually or collectively when called by various combinations of inputs and parameters.

It is the most important type of testing that should be performed throughout all phases of the software development cycle. It can be further divided into different sub-levels depending on the techniques used to perform it, such as:

Unit Testing  – Used during the early stages (to some extent) in the SDLC. A unit, in simplest terms, is a testable software element that can be individually and independently compiled and tested.

Integration Testing  – Used throughout the SDLC to ensure that individual modules function properly when integrated with others. It uses unit testing results as inputs for its tests. This type of testing can also be performed at the system level by using mock objects instead of physical ones, which is known as integration testing.

Again integration testing is subdivided into the Top-Down Approach, Bottom-Up Approach, and Sandwich Approach based on the level of code developed, where Top-Down Approach tests from high level to low level, while Bottom-Up testing starts with low and ends at the top.

Top-Down Approach: This approach is suitable for integrating the modules from high-level to low-level. It starts with a higher-level module and ends at the lower level by combining all the lower-level modules until the requirements of each individual sub-system are fulfilled.

Bottom-Up Approach:  The Bottom-Up approach is suitable for integrating the components from low-level to high-level. It starts with a low-level module and ends at the higher level by combining all the high-level modules until the requirements of each individual sub-system are fulfilled.

Sandwich Approach: Sandwich approach is implemented in situations where components from both Top-Down Approach and Bottom-Up Approach are used together for integration testing.

System Testing  – Used during the late stages in SDLC for evaluation purposes: after systems and subsystems have been integrated but before they are delivered to the customer. In this testing, we focus on system-level compatibility, i.e., that our software works correctly in an environment with other working components, and that it performs as expected.

Acceptance Testing  – Used at or near the end of SDLC during the implementation process wherein quality is achieved by interaction with the client or customer representatives. It focuses more on product requirements and deals with procedural aspects of the software design.

There are different types of acceptance testing like alpha testing, beta testing, and Gamma Testing.

Alpha Testing: This type of testing is usually performed at the end of the SDLC process, once a major portion of the software has already been built. Alpha Testing can be considered as an evaluation stage where the software is first tested with internal (or limited) users to check its suitability for deployment.

Beta Testing:  Testing by customers or potential users of a system or application. The purpose of Beta Testing is to verify the quality of the software product and to identify any errors, defects, and issues with a view to improving its overall performance.

Gamma Testing:  Performed when the final phase of SDLC has already been completed wherein software testing for an external client or customer takes place. Gamma testing is performed by an independent party or consultant hired for the specific purpose of evaluating the software.

Non-Functional Testing (NFT): This type of testing is used to evaluate how well an application meets non-functional unstructured criteria such as performance/speed, security, portability, etc. In this type of testing, we are less concerned with the correct behavior of software and more focused on how well it does certain things.

I love open-source technologies and am very passionate about software development. I like to share my knowledge with others, especially on technology that's why I have given all the examples as simple as possible to understand for beginners. All the code posted on my blog is developed, compiled, and tested in my development environment. If you find any mistakes or bugs, Please drop an email to softwaretestingo.com@gmail.com, or You can join me on Linkedin.

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