What is Software Testing? Definition, Types, and Tools

What is Software Testing?

Software testing is the process of checking if the quality, functionality, and performance of a software meets expectations. Testers either interact with the software manually or execute test scripts to find bugs. There 

Software testing is a crucial part of the software development life cycle. Without it, app-breaking bugs that can negatively impact the bottom-line may go undetected. Over time, as applications get more complex, software testing activities have also evolved, with many new techniques and approaches introduced.

Approaches To Software Testing

QA professionals have 2 different approaches for software testing: manual testing vs automation testing. Each approach carries its own set of advantages and disadvantages that testers must carefully consider to maximize test resources.

• Manual Testing: Testing software manually by humans without any automation tool or script
• Automation Testing: Testing software using tools or scripts that automatically interact with the software. The human tester only needs to execute the script and let it do the rest of the testing.

Why is Software Testing Important?

The road of software development is bumpy, and products can always be vulnerable to bugs and defects. It is necessary to ensure that software works as expected before being released to the market. Here are several reasons why software testing is essential:

1. Detecting defects for the development team to address

The end goal of software testing is always to uncover bugs and defects. Modern software is built from highly interconnected components that must work together seamlessly to deliver the intended functionality. One broken component can create a ripple effect and break the entire app. The sooner the broken code is fixed, the smaller the impact. A good testing process in place ensures that a higher quality and more reliable product is always delivered on time.

2. Maintain and enhance product quality

Product quality is more than just the absence of bugs. When we think of quality, we think of the characteristics that not only meet but also exceed customer expectations. An application is expected to perform the functions it was intended for, but it can only achieve the status of “high-quality” when it goes above and beyond those expectations. From this perspective, software testing is the key to quality, for the following reasons:

• Maintain
  • Regression testing to ensure that the quality is always kept at a consistent standard after adding new code
  • Periodic usability, compatibility, and security testing to ensure that these aspects of the software are kept well under check
  • Provide insights on product quality for the dev team to continuously update documentation
• Enhance
  • Identify and address bugs to make the software more reliable
  • Identify areas for optimization and improvement
  • Ensure that software functionality work as expected
  • Ensure that the software aligns with user feedback
  • Ensure software compatibility across platforms and environments

3. Improve customers' trust and satisfaction

The result of rigorous software testing is improved customers’ trust. Although it is unrealistic to expect a completely bug-free software, having a product that is stable, reliable, and constantly meeting the customers’ needs will eventually lead to positive user experience in the long term. Adopting software quality management best practices assures stakeholders and customers that they can rely on a product that has been tested multiple times.

4. Identify vulnerabilities that can save company costs and even human lives

Financial, medical, legal software or any types of software in the YMYL (Your Money Your Life) field deal with sensitive information. Software applications built for these fields can’t afford to undergo crashes, data corruption, or system failures, even at small scale, because the lives of so many people will be affected. Errors in these software may cause irreversible damage and put the company at risk of litigation. Software testing is there to protect companies from such risk.

Check Out Top Automated Software Testing Tools

What Does a Software Tester Do?

From the mission of software testing, you can immediately infer the mission of a software tester, which is to:

1.  Find bugs fast, check bugs even faster 
2.  Provide a general assessment of the product quality
3.  Ensure that the product meets quality standard
4.  Improve product quality over time
5.  Educate stakeholders involved in the process about testing best practices
6.  Establish a testing process and continuously optimize it
7.  Minimize cost, time, and effort involved in testing

Types Of Software Testing

Different types of software testing can be classified into multiple categories based on test objectives, test strategy, and deliverables. Currently, there are two major software testing types that Quality Assurance professionals frequently use, including:

• Functional Testing: a type of software testing to verify whether the application delivers the expected output.
• Non-functional Testing: a type of software testing to verify whether the non-functional aspects of an application (e.g., stability, security, and usability) are working as expected.

These umbrella terms encompass a wide range of testing types, each serving only a specific purpose. These are the main types of functional testing:

• Unit testing: a type of testing done on an individual unit in isolation from the rest of the application. A unit is the smallest testable part of any software, usually responsible for only a very targeted set of functionalities. 
• Integration testing: a type of testing where individual units or components are combined and tested as a group to ensure they work together as expected.
• Acceptance testing: a type of testing to evaluate the application against real-life scenarios
• Visual testing: a type of testing to verify the Graphical User Interface (GUI) to ensure that it is presented to users as expected 

Similarly, under Non-functional Testing, there are also many common testing types, each with different objectives and strategies:

• Security Testing: Testing that checks if the software is secure and protects against unauthorized access or threats.
• Performance Testing: Testing that assesses how well the software performs in terms of speed, stability, and resource usage.
• Load Testing: A type of performance testing that evaluates how the software handles expected and peak loads.
• Usability Testing: Testing that measures how user-friendly and easy-to-use the software is.
• Compatibility Testing (or Cross-browser Testing): Testing that ensures the software works correctly across different platforms, devices, or environments.

The decision to use which of these types of software tests depends on the test scenarios, resource availability, and business requirements.

Software Testing Life Cycle

Many software testing initiatives follow a process commonly known as Software Testing Life Cycle (STLC). The STLC consists of 6 key activities to ensure that all software quality goals are met, as shown below:

1. Requirement Analysis

In this stage, software testers work with stakeholders involved in the development process to identify and understand test requirements. The insights from this discussion, consolidated into the Requirement Traceability Matrix (RTM) document, will be the foundation to build the test strategy.

There are 3 main people (the tres amigos) involved in the process:

1. Product Owner: Represents the business side and wants to solve a specific problem.
2. Developer: Represents the development side and aims to build a solution to address the Product Owner's problem.
3. Tester: Represents the QA side and checks if the solution works as intended and identifies potential issues.

To ensure the highest level of understanding between stakeholders, QA teams can employ BDD testing, an Agile approach to software testing where simplicity is valued. Ensuring testability is crucial during the design phase to avoid ambiguous requirements that can lead to invalid software tests. 

After that, testers and developers have to collaborate to understand the feasibility of implementing business requirements. If these requirements can not be met within the given constraints, limitations, or resources, they will need to discuss with the business side (either the Business Analyst, Project Manager, and/or the client) to make adjustments or seek alternative solutions.

Read More: TDD vs BDD: A Detailed Comparison

2. Test Planning

After thorough analysis, a test plan is created. Test planning involves aligning with relevant stakeholders on the test strategy:

• Test objectives: Define attributes like functionality, usability, security, performance, and compatibility.
• Output and deliverables: Document the test scenarios, test cases, and test data to be produced and monitored.
• Test scope: Determine which areas and functionalities of the application will be tested (in-scope) and which ones won't (out-of-scope).
• Resources: Estimate the costs for test engineers, manual/automated testing tools, environments, and test data.
• Timeline: Establish expected milestones for test-specific activities along with development and deployment.
• Test approach: Assess the testing techniques (white box/black box testing), test levels (unit, integration, and end-to-end testing), and test types (regression, sanity testing) to be used.

For a greater degree of control over the project, software testers can add a Contingency plan to adjust the variables in case the project moves in an unexpected direction.

3. Test Case Development

After defining the scenarios and functionalities to be tested, we'll write the test cases. For manual test cases, test management tools like Xray can be used to note down details of what was performed, the results, findings, and suggestions for developers to reproduce those bugs. For automated tests, intuitive UIs provided by tools like Katalon, Ranorex, or TestComplete are available. Open-source options like Selenium, Cypress, and Playwright are also popular for building custom frameworks. 

If you don't know which test cases to start with, here are the list of popular test cases for you. They should give you a good foundation of how to approach a system as a tester. 

1. Test Cases For API Testing
2. Test Cases For Login Page
3. Test Cases For Registration Page
4. Test Cases For Banking Application
5. Test Cases For E-commerce website
6. Test Cases For Search Functionality

The actual number of test cases to be executed depends a lot on the complexity of the system under test. A good tester is one who can think of creative ways to break a system, so when developing your test cases, try to put yourself in the mindset of someone who has absolutely no idea how that system works and find as many ways to go wrong with it as possible.

4. Test Environment Setup

This step can be done in parallel with Test Case Development. A test environment is the software and hardware configurations under which the application is tested, including a database server, front-end running environment, browser, network, hardware, etc. QA teams will plan resource usage for Test Environment development. This practice ensures efficient resource allocation. Here is a quick checklist of items you need to consider when setting up test environment:

• Verify hardware specifications (CPU, RAM, storage).
• Check software dependencies (operating system, libraries, frameworks).
• Validate network requirements (firewall rules, ports, connectivity).
• Ensure the test environment is separate from the production environment.
• Use network segregation, virtualization, or dedicated hardware.
• Identify relevant test scenarios and data requirements.
• Create representative test data sets.
• Consider data privacy and security regulations.
• Install necessary operating systems and software.
• Set up databases, web servers, and other required components.
• Configure network settings, firewalls, and security measures.
• Establish recovery mechanisms to restore the environment to a known state.
• Implement regular backups to prevent data loss or configuration issues.
• Establish recovery mechanisms to restore the environment to a known state.
• Implement regular backups to prevent data loss or configuration issues.

5. Test Execution

With clear objectives in mind, the QA team writes test cases, test scripts, and prepares necessary test data for execution.
 

Tests can be executed manually or automatically. Manual testing is suitable when human insights and judgment are required, while automation testing is preferable for repetitive flows with minor adjustments. Once the tests are executed, any defects found are tracked and reported to the development team, who promptly resolve them.

6. Test Cycle Closure

This is the final phase of Software Testing. Software testers will gather to analyze what they found from the tests, evaluate the effectiveness, and document key takeaways for future reference. It is crucial to regularly evaluate your QA team's software testing progress to remain in control of all testing activities across all phases of the STLC.

Read More: How To Build a Good Test Report?

Types of Application Under Test

There are mainly 4 types of Application-Under-Tests (AUTs):

1. Web Testing
2. API Testing
3. Mobile Testing
4. Desktop Testing

Among these, web testing is the most popular, and it is the also the type of AUT most prioritized for automation in recent years according to the State of Quality Report 2024-25, with up to 81% respondents saying that they have incorporated web automation practices into their processes. Following behind is API services automation.

→ Download the State of Quality Report 2024 here to get the latest insights

What Kinds Of Tests To Do Manually?

Although automation testing has become the norm in the industry, manual testing is still very much needed. Manual testing shines through when QA teams need a layer of human verification. In fact, it is proven that manual testing helps testers discover tricky bugs, i.e. bugs that require 2+ chained interaction with the system to trigger.

Manual tests are ideal for:

1. Exploratory Testing: a hands-on approach where testers explore the application without predefined test cases. Testers can use their creativity and intuition to find bugs that automated tests might miss.
2. Usability Testing: a type of testing that focuses on the user experience and interface design. It’s essential for ensuring that the application is user-friendly and meets the end-users' needs. Manual testing is crucial here because only a human can accurately judge the intuitiveness of the UI and the overall user experience.
3. Ad-hoc Testing: an unstructured and informal testing method. It allows testers to quickly validate fixes or new features without waiting for automated test scripts to be written.
4. User Acceptance Testing: a type of testing performed by the end-users to ensure the application meets their requirements and expectations. End-users can test the application in real-world scenarios, providing feedback that reflects their actual use cases.

What Kinds Of Tests To Automate?

Automated software testing can be leveraged to test large volumes of software components when manual testing becomes counterproductive. Automation brings high ROI and allows QA teams to perform more critical testing activities. A test case is qualified for automation if the following criteria are met:

1. It’s repetitive, and test steps are unlikely to change
2. It’s time-consuming/impossible to perform manually
3. It runs on multiple software/hardware platforms
4. It’s prone to human error

In practice, regression testing usually takes top priority for automation because its nature is to execute the same tests repeatedly. Automation allows for faster regression test execution, enabling QA teams to focus on other critical tasks.

Even when testers don’t really need to automate tests, automation testing tools can still support them in many other areas, such as test reporting and analytics for data-driven decision making. They also offer centralized testing management on which teams can collaborate through many development and testing phases.

Popular Software Testing Models

The evolution of the testing model has been in parallel with the evolution of software development methodologies.

1. V-model

In the past, QA teams had to wait until the final development stage to start testing. Test quality was usually poor, and developers could not troubleshoot in time for product release. 
 

The V-model solves that problem by engaging testers in every phase of development. Each development phase is assigned a corresponding testing phase. This model works well with the nearly obsolete Waterfall testing method.

On one side, there is “Verification”. On the other side, there is “Validation”.

• Verification is about “Are we building the product right?”
• Validation is about “Are we building the right product?”

2. Test Pyramid model

As technology advances, the Waterfall model gradually gives way to the widely used Agile testing methods. Consequently, the V-model also evolved to the Test Pyramid model, which visually represents a 3-part testing strategy.

Most of the tests are unit tests, aiming to validate only the individual components. Next, testers group those components and test them as a unified entity to see how they interact. Automation testing can be leveraged at these stages for optimal efficiency. 

Finally, at the UI testing stage, testers focus on the UX and UI of the application.

3. The Honeycomb Model

The Honeycomb model is a modern approach to software testing in which Integration testing is a primary focus, while Unit Testing (Implementation Details) and UI Testing (Integrated) receive less attention. This software testing model reflects an API-focused system architecture as organizations move towards cloud infrastructure.

Manual Testing vs. Automated testing: Which One To Choose?

When starting any software testing project, the testing team and development team must sit together and develop a test plan, outlining which areas to test manually and which areas to leverage automation testing. A hybrid approach should give testers the benefits of both types, as shown in the comparison table below:

Read More: Automated Testing vs Manual Testing: A Detailed Comparison

Is Automated Testing Making Manual Testing Obsolete?

Automated testing takes software testing to the next level, enabling QA teams to test faster and more efficiently. So is it making manual testing a thing of the past?
 

The short-term answer is “No”.
 

The long-term answer is “Maybe”.
 

Manual testing still has its place in the software testing world. We need humans to evaluate the application’s UX, supervise automation testing, and intervene when necessary. However, AI technology is gradually changing the landscape. Smart testing features have been added to many automated software testing tools to drastically reduce the need for human intervention. 
 

In the future, we can expect to reach Autonomous Testing, where machines completely take control and perform all testing activities. There will be absolutely no need for humans except for the development of testing algorithms. Many software testing tools have leveraged LLMs to bring us closer to this autonomous testomg future.

Top Software Testing Tools With Best Features

Testers have 2 options when it comes to selecting a software testing tool:

• Build a tool from scratch using automation libraries such as Selenium
• Buy a pre-built tool supporting the features they want from a vendor

Both options have their own pros and cons. Simply put, building a tool requires a lot of technical expertise and ongoing in-house maintenance, but the team gets 100% control over what they want the tool to do. Buying a tool is simpler, and although the degree of customization is not as high, all of the hard work of building and maintaining the tool has already been shouldered by the vendor, and the testing team only has to shop for the right tool.

Currently, plenty of software testing tools are available on the market. Here is a list of top software testing tools we have selected for you:

1. The Katalon Platform

The Katalon Platform allows QA teams to author web, mobile, and desktop apps and UI and API automated tests, execute those tests on preconfigured cloud environments and maintain them, all in one unified platform, without any additional third-party tools. The Katalon Platform is among the best commercial automation tools for functional software testing on the market. 

• Test Planning: Ensure alignment between requirements and testing strategy. Maintain focus on quality by connecting TestOps to project requirements, business logic, and release planning. Optimize test coverage and execute tests efficiently using dynamic test suites and smart scheduling.
• Test Authoring: Katalon Studio - a product within the Katalon Platform portfolio - combines low-code simplicity with full-code flexibility (this means anyone can create automation test scripts and customize them as they want). Automatically capture test objects, properties, and locators to use. 
• Test Organization: TestOps organizes all your test artifacts in one place: test cases, test suites, environments, objects, and profiles for a holistic view. Seamlessly map automated tests to existing manual tests through one-click integrations with tools like Jira and X-ray.
• Test Execution: Instant web and mobile test environments. TestCloud provides on-demand environments for running tests in parallel across browsers, devices, and operating systems, while handling the heavy lifting of setup and maintenance. The Runtime Engine streamlines execution in your own environment with smart wait, self-healing, scheduling, and parallel execution.
• Test Execution: Real-time visibility and actionable insights. Quickly identify failures with auto-detected assertions and dive deeper with comprehensive execution views. Gain broader insights with coverage, release, flakiness, and pass/fail trend reports. Receive real-time notifications and leverage the 360-degree visibility in TestOps for faster, clearer, and more confident decision-making.

Download Katalon and Witness its Power in Action

Check out a video from Daniel Knott - one of the top influencers in the software testing field - talking about the capabilities of Katalon, and especially its innovative AI features:

2. Selenium

Selenium is a versatile open-source automation testing library for web applications. It is popular among developers due to its compatibility with major browsers (Chrome, Safari, Firefox) and operating systems (Macintosh, Windows, Linux).

Selenium simplifies testing by reducing manual effort and providing an intuitive interface for creating automated tests. Testers can use scripting languages like Java, C#, Ruby, and Python to interact with the web application. Key features of Selenium include:

• Selenium Grid: A distributed test execution platform that enables parallel execution on multiple machines, saving time.
• Selenium IDE: An open-source record and playback tool for creating and debugging test cases. It supports exporting tests to various formats (JUnit, C#, Java).
• Selenium WebDriver: A component of the Selenium suite used to control web browsers, allowing simulation of user actions like clicking links and entering data. 

Website: Selenium

GitHub: SeleniumHQ

3. Appium

Appium is an open-source automation testing tool specifically designed for mobile applications. It enables users to create automated UI tests for native, web-based, and hybrid mobile apps on Android and iOS platforms using the mobile JSON wire protocol. Key features include:

• Supported programming languages: Java, C#, Python, JavaScript, Ruby, PHP, Perl
• Cross-platform testing with reusable test scripts and consistent APIs
• Execution on real devices, simulators, and emulators
• Integration with other testing frameworks and CI/CD tools

Appium simplifies mobile app testing by providing a comprehensive solution for automating UI tests across different platforms and devices.

Website: Appium Documentation

Conclusion

Ultimately, the goal of software testing is to deliver applications that meet and exceed user expectations. A comprehensive testing strategy is one that combines the best of manual and automation testing.