Key Software Testing Types Every QA Needs to Know
Tags: software, testing, types, testgrid
Published: 2024-04-02 04:31:50

Software testing is a crucial part of the SDLC (Software development life cycle) to ensure that the software program is error-free. Testers need to perform various types of software testing to ensure that all the components of the software are working. 

The following graphic will give you a good idea of the classification of software testing in the hierarchy. 

In this article, we have talked about the different types of software testing, their working methodologies, and practical examples of each. 
		

## Functional Testing

Functional Testing is performed to test if the software works as intended and meets the expectations of end-users by providing accurate results. It evaluates the functionality of software by testing its features and capabilities against specified requirements.

Here, testers prepare various test cases to simulate user interactions, as well as prepare datasets and test software’s functionality for these interactions. 

### Benefits of Functional Testing:

- It ensures that software meets the specific user requirements and meets the end-user’s needs. 
- Testers can address the missing features and identify the gap between the software’s intended behavior and actual implementation. 
- By validating the features that meet regulatory compliance and guidelines, testers can mitigate compliance risks at an early stage. 

**Examples:** 

The examples include anything that performs the working of an application or its certain feature. For instance, functional testing for the “Add to Cart” button in eCommerce websites. 
Or, say, testing the “Search” feature in the music streaming application. 

### 1) Unit Testing

Unit Testing is a crucial part of functional testing. It tests for the individual unit or a particular feature of the software system. Unit tests are automated and are performed in isolation to test each feature individually.

Testers can perform unit testing by writing various test cases to test these codes. This way, they can catch and detect the bugs at an application development stage.

**Benefits of unit testing:**

- Detects bugs and issues at an early stage to save time and money before issues become larger. 
- Performing tests in isolation ensures that the changes in code do not introduce new bugs. 
- Exposes the edge cases and helps you write refactored and optimized codes. 
**Example:**

An application can be logged in using a password that contains eight characters and a symbol. Developers can perform the unit test on these text fields by entering a password with less than eight characters or no symbols. 

**White Box Testing**

White box testing is a technique for evaluating the internal structure of a software system. It tests the internal codes, product architecture, internal design, and code structure to determine the software’s internal performance and efficiency. 
Also called open box testing or transparent box testing, this type of testing is useful for detecting loopholes in the design of the application. The tester has access to the source code and documentation, using which it designs the test cases to test software at the code level. 

**Example:** 

Consider an example of an online portal that requires the sign-up and log in. 
With access to the source code, the testers will perform tests on code responsible for the authorization. This involves inspecting the source codes to test the scenarios like valid user credentials, incorrect passwords, and failed login attempts. 

**Gorilla Testing**

Gorilla testing is a software testing technique that performs a single feature or functionality for errors. The test uses the minimum number of test cases to evaluate the software through all aspects. 

Its purpose is to find as many errors as possible in a short period of time. Hence, it is the best testing technique for the testers when the time is limited. Here, the test cases are chosen at random and the tests are performed consistently to make sure the detected errors are not by chance. 
It increases test coverage since it tests multiple aspects in a single test. 

**Example:** 

Consider a financial institution rolling out a new online banking system. Testers might randomly navigate through different banking services, such as account balance inquiries, fund transfers, bill payments, or loan applications. 
They can test each module of these online banking services for positive and negative scenarios. 

### 2) Integration Testing

[Integration testing](https://testgrid.io/blog/integration-testing-types-approaches/) is a technique for evaluating the functioning of software when two units are combined. The purpose of the test is to determine whether the two features work efficiently for the end users. 

Integration testing is performed after the unit testing to verify that the interface connection works seamlessly and meets the specific requirements. It tests for critical faults such as incorrect data transfer, messy interface, or improper functioning when two features combine.

Integration testing can be performed in three ways: top-down testing, bottom-up, and big-bang testing. 

**Benefits of Integration testing: **

- Makes debugging and error detection easier since faults can be isolated to specific interfaces. 
- Validates the data flow between different systems and processes to ensure data integrity. 
- Provides additional reliability and stability to software functioning. 

**Example:**

 A user adds products to the shopping cart and proceeds with the payment. Here, testers need to perform integration testing for different modules. Integrating testing should be done to check for the working of the product catalog and checkout cart together and the working of the checkout cart and payment processor together. 

**Grey box testing **

Grey box testing is a technique that combines the elements of white box testing and black box testing. The tester has limited knowledge of the documentation and internal working of the system. 

Grey box testing is performed in cases where third-party components or legacy systems are involved. 
The purpose of grey box testing is to identify defects by leveraging the internal and external environments. This way, testers can also prepare the test cases that are specified for some areas or software features that might have issues. It also ensures that performance is evaluated from the external user perspective. 

The best part; it does not require high-programming knowledge since it involves the best of black and white box testing. 

**Example: **

A software company developing a web application integrates with a third-party payment processing service to handle online transactions. The development team has access to the API documentation provided by the payment processor, which outlines how the integration should work, but they don’t have visibility into the actual implementation details of the payment service’s code.
In this case, the testers can perform grey box testing to ensure that the integration between the web application and the payment processing service functions correctly.

### 3) System Testing
 
System testing is performed to test the overall functionality of the software and the performance of a completely integrated system. This test is performed after the integration testing and before the acceptance testing. 
The purpose of system testing is to check if the system meets the specific requirements and hence, is done from the end-user’s perspective. 

**Benefits of System testing:** 

- Efficiently identifies the errors and bugs that may not be detected during the unit testing and integration testing. 
- Checks for system requirements and ensures it offers compliance with regulatory bodies. 
- Replicates the real-time production or business environment.
 
**Example:** 
Take an example of an airline reservation system that involves actions like searching a flight, entering the passenger details, making payment and confirming the payment. The system integrates with various components such as flight databases, payment gateways, and user authentication systems.

Testers will perform various testing types like functional testing,  unit and integration tests individually for these components. System testing will test for tasks like maintaining real-time flight databases, faster processing and secured payments. 

**End-to-end testing** 

This software testing type is the most comprehensive one since it involves testing the entire sequence of actions from user input to the final output. The purpose of this testing is to mimic the real-world use of the software as a whole rather than individually testing a unit or module.
 
End-to-end testing is performed to identify any potential issues or defects in the application, such as integration problems, data loss, security vulnerabilities, and user experience issues.

**Example:**

Let’s say a tester needs to perform all the functionalities of an online insurance site. It tests for the insurer’s details, policy page, calculation of policy, payment processor, connection with third-party, and confirmation receipt. 

**Black box testing** 

Opposite to white box testing, testers do not have access to any internal source codes or processes in Black box testing. Here, testers perform tests based on the provided specifications or requirements without knowing the process of implementation. 
All in all, black box testing only focuses on the input and output of the test objects. 

**Example:** 

Imagine testing the features of a payment gateway. Without delving into the internal mechanism, testers perform tests on the messages displayed in case of wrong credentials or a successful payment message.

**Smoke testing**  

Smoke testing is performed to evaluate the basic and critical functionality of the system. It is also performed to validate that the system under test is ready for further testing. 
It is performed at an early stage of the development cycle or when a new build is deployed. The testing team validates the functionalities of this new build to ensure that it is stable. 

**Example:** 

Assume that there is a music streaming app with over 20 modules. However, the four main components are one-click login, adding and removing the songs, pause and play. Smoke testing doesn’t perform the edge cases but looks into the crucial testing. 
Instead of checking the process, it checks if the one-click login works well. 

**Sanity testing**

Sanity testing is performed to ensure that the newly added function or a recent bug fix works fine for the software and doesn’t interrupt with other functions. This testing type is performed on the stable build and executed after the product has passed the smoke test. 
It validates whether further action in the build can proceed or not. 
**Example:** 
Assume an online store that plans to run discount programs for the premium members on weekends. A sanity test can be performed on the premium members to verify that they get a discount on weekends. 

**Happy path testing**
 
Happy path is usually the first test performed on the new build. This testing type uses the known input to produce an expected output. This testing type is performed within the boundaries of real-world scenarios and each functionality is tested for its compliance with real-world. 
The test cases are designed in a way that lets testers check for the positive flows of the app and how it would look to an end user. 
**Example:**
Let’s take an example of a login page. When a user enters the correct email and password and clicks on sign-in, they should navigate to the next page to perform further actions. 
Hence, the expected output is the valid credentials. 

**Monkey testing** 

Evident from the name, monkey testing is a technique where software is evaluated when a monkey uses it. The purpose of this testing is to test your software application in case of real chaos and how it will react to random and invalid inputs. 
This type of testing does not require pre-defined test cases or knowledge of the full functionality of the system. 
Testers can get an output of actions when a user enters invalid data, switches between the screens, or accidentally taps the wrong button. 

**Example:**

Take an example of a mobile app for an airline company. Testers can perform tests and use inputs like random data, such as numbers in the destination and arrival fields, pressing wrong buttons, or vigorously shaking the screen to see if the app crashes. 

### 4) Acceptance Testing
 
Acceptance testing is the last testing stage before the product release. This testing technique tests all the functionalities and performance of the software/ application from the end user’s perspective. 
The purpose of acceptance testing is to ensure that the application meets the business and user’s specific requirements. UAT analyses the stakeholder’s and user’s behavior by executing the pre-defined test cases and evaluating the behavior in a real-world environment. 

**Benefits of Acceptance testing:**

- Clients are directly involved in the testing process, making a final product as intended. 
- Provides effective communication between developers and end-users.
- Tests are performed for multiple browsers, operating systems and test environments

**Alpha testing** 

Alpha testing is a part of the acceptance testing which is performed by the project team to find as many defects as possible before releasing software to the customers. 
The purpose of this test is to identify the bugs, evaluate each feature and garner user’s feedback.

**Example:**

An eCommerce site under alpha testing will perform the functionalities like searching products through search bar, using the categories, sorting the product catalogs, adding product to carts and checking for the integration of payment gateway with checkout cart and more. 
All of these real world scenarios will be performed by the QA testers or internal team. 

**Beta testing ** 

 Beta testing is the first stage when the product is released for the real users. Here, the software is released to the large pool of beta users that test the functionality of software to give their critical feedback. 
It is considered successful when the customer accepts the software. 

**Example:**

A restaurant chain releases the scan and pay service for the customers. Before announcing it to the public, the company releases it for the loyal customers and gathers their feedback in return for rewards and discounts. 

**OAT**  

Operational acceptance testing checks for the operational efficiency of the app and its usability in the real world. This test is performed by the operations team or a system administrator for evaluating factors such as performance, reliability, security, and scalability when deployed. 
OAT focuses on the following points: 

- Testing of requirements
- Testing the codes
- Installing and Uninstalling apps
- User management and 
- Maintenance of software
 
Example:
A large e-commerce company is preparing to launch a new version of its online shopping platform. The platform has undergone thorough functional testing, user acceptance testing, and performance testing. Now, the company needs to ensure that the platform is operationally ready for deployment in its production environment.
The operational team writes test cases to perform tests for performance, reliability, security and access control, and backup & recovery. 

## Non-Functional Testing

Non-functional testing is a testing technique that tests for the non-functional aspects of the software/ application. It does not perform tests from the user’s perspective but digs deeper into the internal workings of the system. 
Non-functional testing is equally important as functional testing, as it examines the system’s performance, efficiency, security, and compatibility. 

**Benefits of Non-functional testing:**

- Helps identify the bottlenecks and factors that impact the performance. 
- Checks on improving the overall user experience and interface friendliness
- Evaluates the app according to the higher volume of traffic. 

**Example:**

A tester can perform a test to see how the software reacts to an unauthorized action in the system. Similarly, it runs tests to see if the app will slow down, crash or run smoothly when unexpected traffic increases. 

### 1)  Security Testing

Security testing is done to check the system vulnerability in case of external or internal security threats. This testing helps you establish a strong security system for your website/app and identify the potential threats, malicious programs or viruses that affect it. 
It also runs tests to check for secured data management, user management and data recovery. 

**Benefits of Security testing:**

- Helps identify potential threats and security vulnerabilities 
- Tests for various security standards and regulations such as HIPAA, PCI DSS, and SOC2.
- Saves time and cost in the early stage of software development and avoids embarrassing security incidents. 

**Example:**

Take an example of an online financial institution that is launching a banking website. A tester performs security testing to check for unauthorized access, manage password keys, secure communication, and protect data. 
This way, the financial institution can identify and mitigate potential security risks, safeguard customer data, and maintain trust in its online banking application.

**Penetration testing ** 

Penetration testing or ‘Pen testing’ is a testing technique to simulate real-world cyberattacks on the system and identify the weak points and vulnerabilities in the system. 
The test is performed by ethical hackers who perform actions to breach the security systems to identify the vulnerabilities. 
The ethical testers perform various operations such as SQL injection, URL manipulation, session expiry and provide reports to the organization. 

### 2) Performance Testing

Performance testing tests a software/application’s responsiveness, speed, scalability, and stability under normal or peak load conditions. The purpose of this testing is to identify performance bottlenecks, resource utilization issues, and scalability limitations to ensure a seamless user experience. 
The tests are performed in accordance with the industry standards and benchmarks.

**Benefits of Performance Testing:**

- Identify the resource utilization of elements like CPU, RAM and bandwidth during a traffic spike 
- Reduces the risk of crashes, downtime and revenue loss
- Tests for the user experience and customer satisfaction through various test types
. 
**Example:**
An eCommerce website is planning for a major discount program that is likely to garner a significant spike in user activity.  A tester needs to perform a performance test for a sudden traffic spike, response time, CPU utilization and memory usage. 
Performance test helps developers create a system that ensures delivering a fast, responsive, and reliable user experience to its millions of users.
**Load testing**
Load testing determines the system behavior when multiple users use it at the same time. It simulates the real-world load to check its performance under stress. The purpose of this testing is to identify the bottlenecks and see how it will perform under a specific number of users. 
Hence, load testing mitigates the risk associated with heavy traffic loads and slow response times. 
**Example:**
An application system can withstand a maximum of 100 users at a time with a response time of 5 seconds. Testers run load testing to test with a maximum of 100 or less than 100 users. The purpose of the test is to see whether it loads under 5 seconds. 
**Stress testing** 
Stress testing tests for the system behavior and responsiveness by applying load or, say, more users than intended. The main purpose of stress testing is to test systems under exceptional user loads, excessive data volumes, or limited system resources. 
It checks for the system’s breaking points, app crashes and performance degradation. 
Example:
An application system can withstand a maximum of 1,000 users at a time with a response time of 5 seconds. Testers run load testing to test with 1100, 1200, 1300 or more users. The purpose of the test is to see whether it breaks down, responds slowly or performs optimally. 
**Spike testing **

Spike testing is another performance testing technique to assess how a system will perform with a sudden spike in traffic. This test checks whether the system will function correctly when change is made in size or volume of the system and resources and scaled up and down. 
The test is performed to manage the scheduled increase in user traffic, data volume, transaction counts frequency, and more. 

**Example:**

Let’s say, a travel site handles a maximum of 1000 users with a response time of 3 seconds. Testers perform spike testing by increasing the number of users to more than 1,000 users and then gradually increasing the number of users to determine the breaking point or crash. 
Suppose a website may withstand a load of up to 3,000 users and may crash after the 3,100 users threshold. 

**Volume testing** 

Volume testing tests for the system performance when the software/application is subjected to a high volume of data. Also called the floor testing, it works by sending a large volume of data in the database. 
This testing is done to check for the system responsiveness and loading times in case of large volume data. 
**Example:**
Let’s say, a banking mobile app stores X GB of data for storing customer data and other documents. In the next 2 years, the app will have to store 5*X GB of data and in the next 5 years, the app will have 10* X GB of data to store. 

**Endurance testing**   

Another form of stress testing, endurance testing, is a test to check for the system’s performance under a significant load but over an extended period of time. This testing helps identify any potential issues related to memory leaks, resource exhaustion, performance degradation, or other stability problems that may occur over time.
Example: 
A live gaming app that runs endurance testing to ensure that it withstands a large volume of gamers over a period of time like days, or weeks. 

## 3) Usability testing:
 
Usability testing is performed to test the UI and determine how easy the application/software is to use from the end-user’s perspective. The purpose of this test is to check the system’s usability in terms of navigation controls, menu bar, footer, and visual design. 
Testers need to thoroughly work the system internally and externally since it is performed extensively. 
**Benefits of Usability testing:**

- Performs tests from the end-user’s perspective
- Gives a major competitive advantage over others in improving usability
- Check how long it will take to complete a specific task

**Example:** 

Let’s say, a pet eCommerce app has various navigational options and users have to perform usability testing. Testers run the test cases to see if the app can be operated with one hand, reacts to gestures, check usability in horizontal and vertical view and and text overlay with footer and menu. 

**Exploratory testing**

As the name says, this type of software testing is performed to explore the software/applications and identify the defects on the go. This is an unscripted approach where there are no predefined test cases. 
Instead, the test cases are written on the fly as the testers explore the apps. All in all, exploratory testing checks for the functionality, operations and all the technical faults in the system. 

**Example:**

Let’s say, an online banking app has undergone structure testing, integrated and system testing by following predefined test cases. Testers can perform exploratory testing to uncover potential usability issues, edge cases, or unexpected behavior. 
The apps can be run for various browsers, real-time interactions, test boundaries and check for security measures. 
The look and feel of the visuals and interface should be the same in all places. 

**Accessibility testing** 

Accessibility testing tests whether the application or system is accessible to disabled people. By disabled, we mean people suffering from vision impairment, hearing disabilities, and physical or cognitive conditions like color blindness, old age, and others.
Testers need to perform various tests such as font size for the visually impaired, color checks for color blindness, and audio tests for deaf persons. 

**Example:**

 A simple example of how a tester or an SEO would check the alt texts of images in a website or the app. The alt texts in the images can aid individuals who rely on screen readers. 
Testers can run tests and review each image element in the website’s code to ensure that it includes descriptive alt text that conveys the meaning or function of the image accurately.
For instance, a “buy now” button should have an alt text as buy now and not image.1 to ensure it is readable for the visually impaired. 

### 4) Compatibility Testing
 
Compatibility testing is done to test the application performance and how it runs in different environments, web servers, hardware, and network environments. This testing checks for the compatibility of software on different network servers, configurations and respective versions. 
**Benefits of Compatibility testing:**

- Helps detect the bugs during the development stage
- Prepares the software for various network configurations and versions. 

**Example:**

A mobile app that is designed for both Android and iOS has to be tested for various network configurations, Android versions and iOS versions. Testers should perform tests across multiple screen sizes and hardware configurations. 
Compatibility testing checks for inconsistencies, bugs, or issues that may arise on specific devices or operating system versions.

**Cross-browser testing** 
 
This testing type tests a software/application on various real browsers like Chrome, Safari, Edge and others. The purpose of this test is to offer a good user experience on different browser types. 
Example:
A tester wants to check for the usability and functionality of an insurance website or application in different browsers and check the load speed and usability in each. 

**Cross-platform testing** 

Cross-platform testing is a type of testing that tests software/applications on various platforms or operating systems to test for its functionality, scalability and behavior. Testers perform this software testing on platforms like Windows, MacOS, Linux, iOS, Android, or any other platform.

**Example:** 

Imagine a website or on-premise software designed to work on all operating systems. A tester would perform tests on its usability, functionality, and compatibility when run on different operating systems, such as Windows, MacOS, Linux, and others. 

## Conclusion
  
This concludes our extensive list of different types of testing. There are more than 100 other software testing types for testers, but we have highlighted the most used ones.
This blog is originally published at [TestGrid](https://testgrid.io/blog/types-of-software-testing/)