Everything you need to know about Software Testing

What is Software Testing?

In all industries, whenever a new product is developed, it has to be tested for all its features to check whether the product meets all the predefined criteria before being launched among end-users. It’s more so in the IT industry, where applications are tested for their features and functions to give some unexpected results. 

In simple terms, we define independent software testing as a process involving many evaluations and verifications to ensure that the developed software is of the best quality and delivers in all applications and functions as intended.  We remove bugs, lower costs, enhance performance, and provide a greater user experience with software testing. The process encompasses both static and dynamic life cycle activities to assess whether they satisfy all the requirements.

What is the Importance of Software Testing?

Software testing is an integral part of a well-delivered application, and its importance cannot be overstated to the overall development. Some issues in software such as security vulnerabilities, scalability, invalid functions, poor design decisions, or architectural flaws can bring to the surface some unseen or unexpected problems. At the same time, applications are used in real-world use by customers. The surfacing of defects during use by end-users can tarnish a company’s reputation and lead to dissatisfaction and loss of customers – in extreme cases, depending on the use area can cause malfunctions and even human loss.

Its economic significance is not overemphasized because, in 2017 alone, software problems cost businesses and organizations $1.7 trillion in assets. Now think of the 2016 case of Nissan. The company had to call back its 1 million cars when a software defect was found in its airbag sensors detector. Wherever software is used, there is a potential for its malfunction and the appearance of bugs. A software bug in a military satellite was responsible for the loss of $1.2 billion. Apple once paid two hundred thousand dollars for detecting a firmware security bug.

The just mentioned numbers encourage companies worldwide to focus on the right QA processes for the early detection and uncovering of problems before the software reaches the market. In this regard, companies have to upgrade their testing capabilities keeping in mind the advancements in development. In software development companies, the development teams are supposed to be receptive to feedback on the functioning of their applications and address them. A software product delivered flawlessly and performing as per a client’s expectations helps enhance market share and more sales for all the companies. 

What are the Methodologies of Software Testing?

Black Box Testing

Conducted at all levels of testing such as unit, integration, system, and acceptance, in Black Box Testing, testers focus just on the functionalities of the software without going into the internal details and codes. It means the software is checked just for what it is designed to do. Internal programming is not covered in the Black Box Testing. The tester feeds in all kinds of values such as valid values, invalid values, and boundary values, and, based on the expected output, declares whether it passed or failed.

White Box Testing

Opposite of Black Box Testing, in White Box Testing, we conduct in-depth tests to the level of internal programs examining logic, their implementation, and working. It’s carried out at the unit, integration, and system levels and often detects internal design errors. The following codes are covered for testing: statements, conditions, decisions, conditions, and multiple conditions.

In the statement coverage, all the statements of the code are executed at least once to ensure it works as expected.  In the decision coverage, all the true and false conditions of the code are tested, including if statements, for and while loops, and case statements. Condition coverage includes checking all Boolean expressions which return True or False. These are important in the final output, and every one of them is checked.

Grey Box Testing

Grey Box Testing, Black Testing, and White Box Testing are combined by looking into the logical and functional parts of the software. For carrying out this test, a tester is supposed to know the internal structure and architecture of the code as they may need to write the test cases for testing. In big projects, for Grey Box Testing, sometimes automated testing is incorporated.

Incremental Testing

One of the approaches of Integration Testing tests all the modules individually in the unit testing phase. Afterward, the tested modules are integrated gradually, and testing is further built upon gradual integration. Incremental Testing ensures smooth interface and interaction among all modules.

Incremental testing consists of three categories:

  1. Top-down Integration – As the name suggests, it involves integrating modules from top to bottom, with the modules not available replaced by stubs.
  2. Bottom-up Integration– Modules are integrated from bottom to top, with the unavailable modules replaced by drivers.
  3. Functional Incremental– In this, testing is done as per the predefined functional specifications.

Incremental testing helps find out the defects in the early stage; however, the development of drivers and stubs can sometimes be time-consuming.

Thread Testing

We define a thread as the smallest unit of work that a system can do. This testing aims to know if the system can carry out the required functions as per the requirements in the early stages of integration.

What are the Levels of Software Testing?

The testing is generally conducted at the following four levels:

  1. Unit testing
  2. Integration testing
  3. System testing
  4. Acceptance testing

Unit Testing

It is necessary that unit testing be carried out before the beginning of the integration testing. A unit is the smallest testable and independent part of the code for the software. The first step in software testing, unit testing, is carried out by developers themselves and rarely done by testers separately. Once the developers are confident that the units in the code are working fine, they can only send them to the testers for integration testing. If the unit testing is done and the code has been checked for any bugs, a lot of time and costs are saved, and the overall development and delivery process picks up pace.

Integration Testing

Integration testing starts with the work of a testing engineer who checks how the units interact to produce the output in different scenarios.  At this level are detected defects of requirement, function, and performance areas. Three approaches are broadly used for integration testing: Top Down, Big Bang, and Bottom-Up. In Bang, the complete system formed by combining all the modules is tested for bugs. As the name suggests, in the top-down approach, the testing starts with the top-level modules and moves down with the insertion of sub-modules for testing. 

System testing

After completing the integration testing for checking the necessary working and integration of the components, the software is tested by highly skilled test engineers for performance and adherence to necessary quality requirements, technical specifications, and functions as required by the customers. It is purely black-box testing. The system is tested as per the users’ point of view for the software’s behavior and design, validating the clients’ software architecture and business requirements.

Acceptance testing

The final level of testing is carried out to see if the system meets the client’s business requirements and if it’s ready for deployment. It has a wide range of scope, including checking language, cosmetic errors, bugs, etc. The test engineers use various ways, including pre-written scenarios, to test the system and see how the software will perform when the users use it. 

Acceptance testing is further categorized in the following ways:

  • User Acceptance Testing: Carried out by the actual users before the system is accepted, it can be conducted at the developers’ site or the user’s site.
  • Operation Acceptance Testing: It is conducted to ensure that all the necessary processes are working right and the software can be used and maintained easily.
  • Contract and Regulation Acceptance Testing: It makes sure that the system meets all the legal and safety standards and regulations.
  • Alpha Testing: Performed when the software development is nearing the end, it tests the system as a whole and, if done successfully, paves the way for Beta Testing. It makes sure that the system is of good quality and that all the engineering aspects are done as required. It is carried out from the point of users.
  • Beta Testing: Done some days or weeks before the release of the product,  this test further improves the quality of the product by checking all the customer requirements. The users carry it out in the real world.

We can further categorize testing based on who does the test, how to do it, and what and when to do it:

How do you do testing?

It means how the testing strategy is implemented, which can be grouped further into two sections: Manual testing and Automated testing.

Manual Testing

In this, the testers conduct the tests without using any automation tools, and by playing end-users, they find bugs in the system, which are sent to developers for fixing them.

Manual testing has the following categories:
  • Exploratory Testing: The testers are allowed to have some freedom to interact with the software and take action as they deem fit. Depending on their experience and understanding, they do the required instead of following any predefined procedure. Nevertheless, the testers are given some parameters and follow them with a plan. Thus, it is a planned activity though not a scripted one.
  • Manual Regression Testing: Performed manually, it is carried out using already executed test cases to verify that a recent bug fix or any other modification in the code has not unexpectedly affected the software’s features.
  • Test Case Execution: The testers execute assigned test cases, and if there are any bugs, they are compiled into a report and sent to developers for fixing. The process helps to understand whether the software is working as expected.

Automated Testing

In automated testing, pre-scripted test cases are executed using an automation tool to increase efficiency in the testing. Automated testing is employed in cases such as when testing requires a lot of time or repetitive tasks requiring login or registrations.  Undoubtedly faster, it increases productivity and reduces testing times. While being a little costlier, it saves time in the long term. However, it is not suited for conditions like documentation, user interface, compatibility, etc.

Automation testing has the following categories:
  • Unit Testing: Explained levels of testing.
  • API Testing: In API testing, we check Application Programming Interfaces (APIs) directly to see if they meet functionality, reliability, performance, and security requirements.
  • Automated Regression Testing: It is just like manual regression testing, except that it is done using an automated method. 

Who does the testing?

Deciding who is going to do the testing is an important part of the testing. It can be In-house Testing, Outsourced Testing, or Crowdsourced Testing.

In-house Testing

It is carried out by the internal testers of the company that developed the software. It has the good advantages that the testers are well trained and for any issues can be in communication with the developers.

Outsourced Testing 

Here the testing is done by an organization outside the company which creates the software. The testing companies have a large pool of well-trained testers who can do testing quicker and more efficiently.  However, sometimes there can be a problem communicating between developers and testers, as they belong to different organizations, leading to unexpected delays.

Crowdsourced Testing 

There are crowdsourced testing firms that provide professional testing facilities with testers located at different places with access to multiple devices. With more people working on finding bugs and problems in the software, testing is done faster and more efficiently.

When to do the Testing?

Accessibility Testing

It is performed to check whether the software can be used by disabled people as well. There are established guidelines to ensure that the software meets the requirements for being used by differently-abled people. The testers check the system for hearing impairments, literacy problems, visual impairments, poor motor skills, etc. The accessibility testing is not advanced at present, and in the future, more improvements are expected.

Compatibility Testing

The application is tested for checking whether it runs on different environments such as operating systems, networks, hardware, etc.

Functional Testing 

Before the release of the application, its performance must be tested for specific actions or functions of the code or features of the work to be done. This testing is carried out under conditions close to user experiences and with the same operating systems,  hardware, etc., to be used by real users.

GUI Testing 

Graphical User Interface (GUI) testing ensures the correct functioning of GUI, such as the input field, the size of the button, readability, etc. Through GUI testing, it is easier to find regressing errors resulting from application updates. It’s easy to carry out through repetitive and time-consuming.

Load Testing 

An important part of testing, and performed generally with automated tools simulating real-world use, load testing checks the application’s behavior under the users’ actual demands. With load testing, the issues preventing the software from performing under heavy demands are unearthed.

Localization Testing

Sometimes a translation of the language of the application does not convey the intended meaning. Many applications are to be released at locations with different cultures and languages. Localization testing checks the quality and acceptability of the application in different cultures and languages. 

Non-Functional Testing 

It’s not related to any specific function or action but checks the breaking point, at which non-functional parts result in unstable execution. It covers load times not covered in functional testing and makes the application more secure and better.

Penetration Testing 

This is testing for checking the application’s security and its environment when subjected to cyberattacks through malicious programs. Penetration tests use the same methods used by real hackers to uncover the vulnerabilities of the application.


The problems related to the software qualities are not the same for all industries, varying from one industry to another. The severity of consequences also varies.  However, software problems can make a big dent in a company’s brand and reputation. There are varieties of tests selected by the testers depending on the application and requirements. There’s no test fitting all the requirements and applications.