Levels of software testing

29.06.2021 / 16:35

4 Levels of Software Testing: how to develop a reliable product

Software Testing checks the behavior of your application during the development process and prevents the occurrence of critical errors, saving your budget. 

According to Software Testing News, if you find errors during the development of your system, you may pay only $25 for a bug. However, the cost of fixing these bugs after launching the software can be up to $16,000. How to properly conduct testing and avoid additional expenses? 

Essential steps of Software Testing

Software Testing is carried out throughout the entire product development lifecycle. This procedure helps to make sure that the product will be able to function successfully in the market. 

Before the release, any software product passes 4 main levels of testing that allow the development team to ensure the correct operation of the system: 

  • Unit Testing;
  • Integration Testing;
  • System Testing;
  • Acceptance Testing. 

The pyramid of test

The purpose of all these testing levels is to make the software testing process more systematic and easily identify all possible app errors. How can these four levels improve your system?

Unit Testing

Unit testing is the first level of software testing. At this stage, developers test individual units of the system to make sure that they are usable.

A unit is the smallest software component that usually performs a single cohesive function. Depending on the development technique, it may be represented by a separate function, a software process, a class, or a method.  

Benefits of unit testing

At first glance, unit testing may seem like a long process since developers discover many defects and constantly make changes in the code. However, this approach gradually makes the code more robust and allows you to find errors at the early stages of software development, saving your time and money.

Integration Testing

During the Integration Testing, QA Engineers combine individual units and test them together as a group. The main purpose of this software testing level is to find bugs in the interaction of system units.

Integration Testing

There are two kinds of Integration Testing: 

  • Top-down Integration Testing
    In this method, QA Engineers perform testing from the highest-level units to the lower-level ones, following the control flow or architectural structure. If some units are not ready, specialists use stubs that act as their temporary replacement.
  • Bottom-up Integration Testing
    The bottom-up integration technique assumes that the tester first checks the lowest-level units and then moves us to the higher-level units. This approach is useful if all or almost all units of the level are ready. 

Each of these approaches has its advantages and disadvantages. However, the choice of Integration Testing type depends on various factors, such as the cost of the application, its complexity, etc. 

System Testing 

System Testing is the phase where a tester checks a complete and fully integrated system as a whole. At this stage, QA Engineers integrate all units to verify whether the developed product works properly and meets the specified requirements. 

By the way, System Testing is a Black Box type of testing. It means that testers study the software without knowing the internal code structure, implementation details, and internal paths.

In this case, quality specialists rely on the specification and check the system for compliance with predefined requirements. 

Acceptance Testing 

Acceptance Testing is the last level of software testing that is carried out before the product goes live. Testers conduct this type of testing to help the customer evaluate the obtained result and check whether the system meets the acceptance criteria.

Acceptance criteria include conditions that allow you to determine when your User Story is completed and has all the functions necessary to meet user needs.

Alpha and Beta Testing

There are two kinds of Acceptance Testing: 

  • Alpha Testing
    Alpha testing is performed by QA Engineers or developers to study the designed software from the client’s point of view.

    At this stage, testers use both White Box and Black Box Testing Methods. It means that software testing engineers not only test the inputs and outputs but also see the system code.
  • Beta Testing
    After Alpha Testing is completed, you can start Beta Testing to improve the quality of the product.

    The main difference between Beta Testing and Alpha Testing is that Beta Tests are conducted by a group of actual users: using Black Box Testing, your target audience evaluates the result of the development team’s work and helps them find possible bugs. 

Alpha and Beta Testing are characterized by different processes, strategies, and goals. However, despite these differences, these two types of acceptance testing help to strengthen confidence in the launch of the system and thereby achieve the success of the product in the market. 

Benefits of Software Testing

During the development process, software products undergo four levels of testing: Unit Testing, Integration Testing, System Testing, and Acceptance Testing. Each of these stages is important and checks the parts of the project with the corresponding complexity. 

A gradual increase in the number of code components in the test helps to easily detect system errors at an early stage and avoid failure of a software product. 

Exposit provides high-quality software testing services using modern approaches and methodologies. We have strong skills in different types of testing and can help you with the full cycle of testing activities. Contact us if you value usability, performance, and functionality and want to deliver only stable products to the market.