Types of Software Testing: Definition, Objectives and Advantages

A fully functional software product is like a mirror image of your business’s reputation. That’s why businesses all over the world are on a constant lookout for a testing team to test their applications. Because of these immense need, the global software testing market is predicted to grow at $70 billion by 2030.

But without proper testing, the bugs and errors not only cost you a hefty amount of money but can also tarnish your business reputation. And so, the demand for software testers, QA, and developers is expected to grow at 25% between 2021-2031.

If you are curious to know – what are the different types of testing? How to select the best one for your project? What are the advantages of a specific testing technique? This blog will serve as a guide for you.

To begin with, software testing is categorized into two broad categories – functional testing and non-functional testing. All types of software testing can be classified under one of the above categories. Let’s start with the definition of functional testing.

Functional testing is carried out to test the software against its functional requirements/specifications. Such tests don’t consider how a process occurs. Instead, it focuses on the intended result of the process. Thus, it answers the most fundamental question “does the application work as intended?”

It has mainly four objectives as follows –

• To test the core functions of the application.
• To test the basic navigation and usability of the application without any hindrance.
• To check the accessibility of the system for the user.
• To test for any error conditions and whether suitable error messages are displayed.

Functional testing is usually carried out in four different testing levels: Unit, Integration, System, and Acceptance. Let’s look at the different types of functional testing and have an in-depth understanding of the different functional testing levels.   

#1 White box and black box testing

White box testing can be implemented in 3 levels of functional testing: unit testing, integration testing, and system testing. In this technique, the tester is aware of the software’s internal infrastructure and the code. It tests the core aspects of software such as input and output, decision branches, loops, statements, etc.

Contrary to the white box testing technique, black box testing is conducted in a completely unknown environment. Here, the tester has neither access to internal code nor possesses any prior knowledge associated with the software. The black box testing technique applies to all four levels of functional testing. While dominantly used for functional testing, black box testing can also perform a variety of non-functional testing.

#2 Unit testing

Software is a combination of different individual parts. Unit testing validates the functions of a specific part or unit. Such type of testing is carried out during the initial phases of software development. This omits the possibility of fixing errors during later stages of STLC, which is sure to incur more time and money.

Unit testing is carried out using the following four techniques.

• Branch Coverage –  This technique tests for all the logical paths and conditions. For example – for an if-else statement, nested for loops, etc. Branch coverage makes sure that each decision condition from every branch is executed at least once.

• Statement Coverage – It is one of the most basic coverage criteria. Statement coverage is used to calculate the number of statements in the code that have been executed. 

• Boundary Value Analysis – This test is performed to analyze the boundary values. For example – a month consists of 31 days. In this scenario, the boundary value lies between 1 and 31. The testing technique will also test values outside of boundary values, i.e., 0 and 32, for invalid conditions.
• Decision Coverage – This testing technique is carried out to report the outcomes, i.e., true or false, for each boolean expression in the source code.

Advantages of unit testing

• Granular testing makes it easier to pinpoint defects.
• Going through documented outcomes of unit testing enhances onboarding employees’ understanding of a particular function.
• Allows the tests to be carried out as independent modules without having to worry about other system components.

#3 Component testing

Similar to unit testing, component testing accesses the individual parts of an application. Therefore, it is also termed Module testing. While the unit testing is carried out by the developer, component/module testing is done by a QA under black-box format. Sometimes QA professionals use a stub and driver to simulate the interaction between components relying on each other. 

For example, consider a huge web application that starts from a basic login page. In the real-life scenario, QA’s can’t wait for the whole application to be built before testing can take place. So, as soon as the login page is developed, QA starts executing test cases to ensure that the login page is functioning as desired.

Advantages of component testing

• UI is tested for usability during the initial phases of development.
• Allows the application to be tested against SQL injections for security reasons.
• Helps in faster delivery of the software product by reducing the development life cycles.

#4 Integration testing

As the name suggests, integration testing is concerned with software modules being logically integrated and tested as a group. After the unit testing, different modules of the software are clubbed with each other. Integration testing is carried out to validate the interaction between different modules as expected. There are three different types of integration testing as follows –

• Top-Down approach – Here, the top-level module is tested first, and then the low-level modules are integrated on top of it.
• Bottom-Up approach – In this, the low-level modules are tested first, and gradually higher-level modules are added. 
• Hybrid approach – It is the combination of both the above approaches. The testing begins at both levels in the hybrid approach and converges in the middle.

Advantages of integrated testing

• As integrated tests have at least two endpoints, it offers QA teams to test many parts in one go. 
• Useful to track system defects in the earlier stages of Software Testing Life Cycle (STLC).
• Helps testing modules to interact with API and third-party tools.

#5 System testing

After the individual models are tested for integration, the crucial system testing comes. Here, all the modules are clubbed together, and the entire system is tested for system failures or errors. The primary purpose is to evaluate end-to-end system specifications. This type of testing is subdivided into 50 different types of tests, but every software testing company uses 3 of the basic tests, namely –

Regression testing

It tests for the integrity of the whole system throughout the development process. Regression testing also ensures that old bugs don’t reappear after adding new software modules.

Functional testing

Here, the tester ensures that there is no missing function within the system. 

Recovery testing

In this type of testing, the tester checks for the reliability of the system and its ability to successfully recover from possible system crashes.

Advantages of system testing

• Ensures that the system performs optimally without crashes.
• It gives a broader perspective of the end product.

Assures stakeholders by showcasing the project’s ability to deliver business goals.

#6 Acceptance testing

This is the last phase of a software’s functional testing before it is made available to the end-user. Next, the client tests the system for its acceptability by verifying if the product performs flawlessly in compliance with business requirements and functionality. The final word lies in the client’s hands to decide whether the system is a Go/No-Go before releasing the product into the market.  

There are majorly three different types of acceptance testing.

Alpha testing

Alpha testing is a subset of acceptance testing carried out by the internal team members. The goal of alpha testing is to detect major bugs in a yet-to-be-stable version of the project.

Beta testing

Here, the application is made available for a selected number of end-users enabling them to provide feedback. Beta testers being end users have no prior knowledge of the application beforehand. This helps get a completely unbiased opinion from a specific set of end-users.

User acceptance testing

Also termed end-user testing, user acceptance testing determines whether the application works as intended for the end-user. This type of testing explicitly checks the functionalities that are quite often going to be used by an end-user. 

Advantages of acceptance testing

• Omits the misalignment between tech teams and management
• Shows red flags that can save from financial and reputational losses.
• Instill confidence in stakeholders and business owners.

Apart from the 6 major types of functional testing mentioned above, there also exist three different types of testing. These tests are performed from time to time to check the software’s reliability, performance, and stability. These are –

Interface testing

For testing the communication between two different softwares that takes place via an interface. Performing interface testing ensures software security and its capability to handle network failure. 

Smoke testing

An end-to-end software testing technique performed to assess the core functionalities of the software. Performing it helps you detect 80% of bugs during the early stages of STLC and also assists you in faster troubleshooting of regression bugs.

Sanity testing

Performed to check any functional issues of the software as a whole after the introduction of new features/changes. Performing sanity testing will help you identify missing dependent objects.

Non-functional testing is the second primary type of software testing. Conducted after the functional tests, the purpose of the non-functional testing is to check the application’s readiness from a non-functional perspective. Here testers deal with all the non-functional aspects of the application like – performance, reliability, scalability, etc. 

Advantages of non-functional testing

• Helps in performance optimization of the product
• To collect performance metrics for internal research and improvements.
• To test the application behavior.
• Ensures faster loading and application responsiveness
• Adds a higher level of security. 

#1 Volume testing

Volume testing ensures that the application responds as intended in scenarios where it has to deal with high volumes of data. Typically when dealing with massive data sets, it impacts the system’s performance. Volume testing ensures that the system impact is within a tolerable limit as per testing standards. Thus, it can act as a benchmark to calculate the current system’s scalability.

Advantages of volume testing

• The system can be prepared for future scalability in terms of data
• Reduces the maintenance of the system by identifying failures arising due to data volume
• Decreases the overall risk of failure due to the sheer volume of data

#2 Localization testing

When the software is developed for global use, a localization test is performed as one of the non-functional tests. The purpose of localization testing is to test the linguistic and regional aspects of the application in accordance with the particular geographic location. This is to test if the software is customized as per the targeted country. The testing process is thoroughly checked against parameters such as local language, currency, date format, etc. Content and UI are the two major areas that are affected by localization testing. 

Advantages of localization testing

• Reduces the overall support cost
• Localization testing has more flexibility and scalability
• Generates end-user loyalty by providing the best user experience and regional language support.

#3 Performance testing

Performance testing consists of a series of tests to check whether the software is performing optimally. It is classified as a non-functional testing type as it deals with performance testing of the whole application rather than focussing on flagging the functional errors. It is a crucial test as it can improve traffic retention by fine-tuning the app’s performance. There can be a multitude of testing types under the domain of performance. However, let’s have a look at the five commonly used types.

Load testing

In this type of testing, the QA induces an expected load on the application and analyzes its performance. Load testing gives a generic idea of an application’s behavior under normal conditions, latency, and throughput.

Stress testing

To check the system’s reliability, the system is subjected to more than the expected workload in stress testing. By doing so, you will get a clear idea about the difference between its intended usage limits and design limits.

Scalability testing

This type of testing verifies the scalability factor of the software. By gradually increasing the number of users, data, and transactions, the evaluation conducted gives a rough idea of the software’s potential scalability factor for future reference.

Spike testing

Unlike load and stress testing, where the workload is gradually increased, the system is tested under a burst of load in spike testing. It analyzes how the system will function under sudden traffic spikes. 

Soak testing

Soak testing is elongated load testing, where the application is analyzed for long-term effects like – memory leaks, storage problems, etc. The duration of soak testing can last up to several hours.

Advantages of performance testing

• Improves the application’s potential to scale.
• Ensures that the application delivers the vision of the project.
• Ensures that the users receive a final product that they can use without frustration.

#4 Usability testing

What’s the use of customer-centric software if it’s too complex to use? Usability testing is conducted precisely to address this issue. The application’s ease of use is tested from the end user’s perspective in this testing method. In addition to that, usability testing helps test the design aesthetics and various workflow processes of the software. 

Advantages of usability testing

• It helps in analyzing user satisfaction while using your software 
• Discerns the client’s needs and concerns
• Analyzes the performance to check if it meets the usability objectives

#5 Monkey testing 

It is a unique type of non-functional testing. As the name suggests, this type of testing is done by assuming a monkey is using the application. Here the tester inputs random input and values and ensures that the application doesn’t get crashed from random inputs. As randomness is the key element to this type of testing, no specific test case is prepared for this test.  

Advantages of monkey testing

• It is used to find out-of-the-box errors.
• The randomness of monkey testing helps in finding bugs that can break the system.
• It can be accessed by anyone who has complete knowledge of the system as well as someone who knows nothing about the application.

#6 Security testing

When the application is running on the server for the end user’s use, the system can be subjected to all sorts of vulnerabilities like virus attacks, malware threats, phishing, data sniffing, etc. Security testing is conducted to identify the potential threats to the application and gauge the overall risk. This analysis will then help security experts take the necessary measures to keep the hackers and data phishers at bay. Security testing can be further classified into four different types of testing as follows –

Vulnerability scanning

It is associated with identifying the known loopholes and vulnerabilities of the application. 

Penetration testing

A type of testing where QAs stimulate a real-time cyber attack on the system under normal conditions. 

Risk assessment

Risk assessment simply means identifying all the software risks and classifying them as high, medium, or low based on their risk factor. 

Security audit

Also referred sometimes as security review, it is a structured process of reviewing the entire application in accordance with defined testing standards. 

Advantages of security testing

• Testing your cyber-defense capabilities
• Reveal unknown vulnerabilities.
• Having a third party expert opinion.

#7 Reliability testing

So the software is ready for your business, and it delivers all the functionality as per your needs. But how reliable is the software in the real-life scenario? What are the chances of it failing? To address these important questions, reliability testing is performed. Under this type of testing, the QA ensures that the software performs optimally for a set time duration under normal load conditions. In addition to that, reliability testing reduces the post-deployment cost by identifying repeating failures.

Advantages of reliability testing

• Ensures that the system can reliably perform for a set period of time with nominal load
• Checks each operation of the software at least once
• Used to find the structure of repeating failures.

#8 Compatibility testing

It is used to measure how the software will work in different environments. This test checks for compatibility with other browsers, operating systems, platforms, or screen resolutions. The business goal of compatibility testing is to ensure that the software is supported across all the environments that the targeted users might be using. 

Advantages of compatibility testing

• Enhances software development process
• Identifies compatibility issues like UI defects, font and color variations, broken tables and frames, etc. 
• Ensures various browsers and devices compatibility

#9 Portability testing

What if, in the near future, you decide to move the server solution? The reason could be anything from server upgrade to scalability or reliability of the server. This type of testing determines the degree of feasibility in porting from one server to another. Therefore, it is crucial to conduct this non-functional testing to make sure your application is future-proof. 

Advantages of portability testing

• Helps in application scalability
• It helps in dependency identification between two applications.
• Ensures flawless performance on most common browsers and devices

Testing is like a tool. How to utilize the tool depends on the master using it. That’s why managers and CTOs must understand the different types of testing. This blog has included all the major testing types and categories commonly used by IT professionals. Which one from the above testing techniques did you find the most interesting? Do let us know in the comments below.