What is the difference between a software tester and a quality assurance engineer? What are the key types of software testing? When and why should you use each of them? And finally, what is software testing? Why should it become an indispensable part of the software development life cycle?

Let’s have a closer look at the essence of software testing and the professionals involved. 

What is software testing, and what is it used for?

As per IEEE Standard 610.12-1990, software testing is “the process of analyzing a software item to detect the differences between existing and required conditions (that is, bugs) and to evaluate the features of the software items”. In other words, software testing allows specialists to check whether the actual software matches previously outlined requirements and to verify that product is a defect (that is, bug) free. 

Quality assurance, in its turn, is a more comprehensive notion. It’s a set of tools, techniques, and activities intended to ensure quality during the software development process. To be particular, QA guarantees that the developed software meets and complies with the defined or standardized quality specifications.

So, QA activities are performed during the whole Software Development Life Cycle (SDLC). They reduce development costs and increase customer satisfaction with the product. Software testing, on the contrary, is just a part of the process. It is conducted after the implementation of certain functionality or completion of development and focuses on processing bugs.

Who are the people involved in the software testing and QA process? 

Software tester, QA engineer, and SDET engineer are the wizards of the software testing and QA processes. However, people often mix up these roles and professional responsibilities. Let’s figure out where the difference is.

Software tester QA engineer SDET engineer
Role description  Checks software for defects and ensures that the product is bug-free.   Develops testing strategy and ensures the quality of the product.   Works in both development and testing roles.
Activity type Bugs detection. Testing tools and methods selection.  Product development and bugs detection.
Aim  To control the quality.  To ensure the quality. To ensure stability, robustness, and performance.
Focus Preventive Corrective Both 
Orientation Product-orientated  Process-orientated  Both process- and product orientated.

Changes in the software development process heavily reflect on testing. The outcome of these transformations is the appearance of such roles as QA engineer and SDET. To sum up, SDETs incorporate testing into the development process. QA engineers have in-depth knowledge of various testing processes, methodologies and are responsible for building effective testing strategies. Software testers, in their turn, ensure that the software is bug-free.

What are the types of software testing, and when should you use each one?

Surfing the internet, you can find over 50 types of software testing. And this variety may be confusing. How do you then know what type of software testing you need? 

As a rule, the software testing types are grouped by:

  1. the testing object
  2. the automation level
  3. the system knowledge level
  4. the level of components’ isolation
  5. the software testing stage
  6. the scenarios positivity and the preparation degree

Each type of testing has its features, advantages, and disadvantages as well. It’s time to take a closer look, and we’ll walk you through the groups of software testing types to define when and why to use them working on a digital product.

By the testing object

This group includes: 

  • Functional testing 
  • Performance testing 
  • Usability testing 
  • Localization testing 
  • UI testing 
  • Security testing 
  • Compliance testing.

To evaluate specific features and their compliance with all initial requirements, opt for functional testing. Performance testing will allow you to check the software speed, scalability, stability, and declared performance under expected workloads. And usability testing enables you to perform user actions and validate the results against your expectations.

You’d better not miss out localization testing to make sure that the application is customized for each targeted country, language, or location. With UI testing, you can look at the product from the end-users perspective and check the lookout of the user interface (that is, menu bars, toolbars, colors, fonts, sizes, content, buttons, etc.)

Security testing uncovers current and potential system vulnerabilities identifies threats and data security from possible intruders. 

And finally, compliance testing determines system compliance with the declared requirements the company follows.

By the automation level

Here we have: 

  • Manual testing 
  • Automation testing 
  • Semi-automation testing. 

During manual testing, a tester manually checks software for errors, defects, or vulnerabilities from the end-user perspective, following pre-defined test cases. Such popular automation testing is performed with the usage of special automation testing tools and test scripts written by a tester and with little or no human interaction to provide greater test speed, coverage, and efficiency. Semi-automated testing combines both above-mentioned types.

By the system knowledge level

Based on testers’ access level to software components and their overall knowledge of it, this group includes:

  • White-box testing
  • Black-box testing
  • Gray-box testing.

White-box testing allows checking the interface without examining the application code or internal structure. Black-box testing assumes working directly with the code to detect bugs or errors. Gray-box testing takes on using a mixture of both. A tester has access to internal data structures to design test cases but is obliged to test at the code level.

By the level of components’ isolation

  • Unit testing
  • Integration testing
  • System testing

Unit testing checks the smallest testable parts, separate components of the system to verify whether they cope with the assigned tasks. Integration testing is performed to reveal faults between integrated system units, the degree of their interaction with each other, fault tolerance, and the impact they have on the system functioning. System testing helps to validate the entire product performance, both software architecture and business requirements in the environment that closely resembles the production one.

By the software testing stage

  • Before the deployment
  • After the deployment.

When is it better to start testing: before or after the deployment? It depends on various factors, like your budget or product complexity. The answer to this question not only explains these two types of testing but also sets the overall strategy for the QA processes building on a project.

By the scenarios positivity and the preparation degree 

  • Positive testing 
  • Negative testing
  • Documentation testing 
  • Intuitive testing.

Positive testing verifies whether the software works as expected, per specified requirements with the valid data input. Negative testing allows you to ensure that the system can deal with invalid data input or unforeseen user behavior.

Documentation testing enables you to make sure that the software description properly reflects how the system works. Moreover, it guarantees that documentation is clear and covers all the particularities and functionality of the software.

Bypassing the necessity to follow test cases, intuitive testing is entirely based on a tester’s skills and experience. Thus, it allows testers to predict potential defects and uncover ones overlooked during systematic testing, support, and documentation testing.

Even though there are many types of software testing, a consultation with a specialist will help you identify the ones you need for your product. Who wants to skip such an important stage of the SDLC as testing or QA and scarify the product quality, reputation on the market, and income in the long run?


In sum, software testing and quality assurance cover the broad spectrum of activities to ensure the quality of software products. Software testing is often associated with a product in terms of finding bugs, while quality assurance is more concerned with the process of testing and compliance with requirements. The same applies to professionals providing quality control and testing. 

It is significant to understand that both software testing and QA services aim at delivering high-quality and stable software that can win your customers.

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