What is Software Testing? Types, Importance, Best Practices and Tools

Yogesh By Yogesh

“Quality is not an act, it is a habit,” as Aristotle once said. To follow this habit in the software engineering realm, you need to carry out software testing.

In generic terms, software testing assesses software qualities and improves the software by finding defects. Several testing methods exist today, and there is no one-size-fits-all approach suitable for a situation. Rather, testing methods exist in a complex space of trade-offs, and often complement each other, and so are used in combination.

To dissect, software testing combines the process of evaluating, reviewing, inspecting and doing desk checks of work products such as requirement specifications, design specifications and code and the process of evaluating a system or component during or at the end of the development process to determine whether it satisfies the specified requirements.

The rise of AI, Cloud, and CI/CD has transformed the way software testing is performed. Automated testing has slowly taken over manual testing, and the arrival of advanced QA tools have remarkably improved the testing process. Use of Jira and GitHub has become common amongst development teams in testing processes, and there is an endless list of tools at their assistance.

Since the scope of software testing is wide and you must become pretty familiar with its in and out, we cover all its facets and explain the concept comprehensively.

What is Software Testing?

Software testing is an integral part of quality assurance, aimed at ensuring that software products meet predefined quality criteria and user requirements. It focuses on identifying defects early in the development lifecycle, preventing costly errors, and improving the overall reliability and usability of the software.

Technically, software testing involves the execution of software components or systems to identify defects, errors, or discrepancies between expected and actual outcomes. It employs various testing methods, such as unit testing, integration testing, system testing, and acceptance testing, to validate the functionality, performance, and reliability of the software.

Software Testing: A Timeline

1947: Grace Hopper discovers a moth trapped in a relay of the Harvard Mark II computer, coining the term “bug” to describe a glitch in a computer system.

1957: The term “debugging” becomes popularized as computer scientists work to remove errors from code.

1972: Gerald Weinberg’s book discusses the psychology behind software development and the importance of rigorous testing to catch errors.

1979: Glenford Myers publishes “The Art of Software Testing,” establishing fundamental principles of software testing and emphasizing the importance of early testing.

1987: The International Software Testing Qualifications Board (ISTQB) is established to standardize software testing practices globally.

2001: The Agile Manifesto emphasizes the importance of iterative development, continuous testing, and collaboration between software developers and software testers.

2004: Selenium, an open-source automated testing tool for web applications, is released, revolutionizing web testing practices.

2008: Continuous integration and continuous testing practices gain prominence, enabling rapid and frequent testing throughout the development process.

2010s: The concept of “shift left” testing emerges, advocating for testing to start early in the development lifecycle, ideally at the requirements phase.

2016: DevOps practices integrate development and operations teams, leading to a culture of continuous testing and deployment.

2020s: Artificial intelligence and machine learning technologies are increasingly applied to software testing, automating test generation, execution, and analysis processes.

How does Software Testing Life Cycle work?

As a structured process, software testing life cycle takes an application through a sequence of these steps:

  • Requirement Analysis: Testers analyze these requirements to determine testable features and define test objectives.
  • Test Planning: Testers identify test scenarios, prioritize them based on risk, estimate testing efforts, and allocate resources accordingly. Test environments are defined and the necessary tools and techniques are identified.
  • Test Case Development: Testers develop detailed test cases specifying test inputs, expected outcomes, and test execution steps. These test cases serve as the foundation for executing tests in subsequent phases.
  • Test Environment Setup: Test environments are prepared to replicate the production environment as closely as possible. Testers set up hardware, software, network configurations, databases, and other dependencies required for testing.
  • Test Execution: Testers execute the prepared test cases in the designated test environment. They report any deviations between expected and actual results as defects.
  • Defect Reporting and Tracking: Defects identified during test execution are reported in a defect tracking system. Each defect is assigned a severity and priority level, and the status is tracked throughout the defect resolution process. Detailed information about the defect, including steps to reproduce, environment details, and screenshots, is provided for effective resolution.
  • Defect Resolution: Developers analyze reported defects, reproduce them in their development environment, and fix the underlying issues. Once resolved, the fixes undergo verification by the testing team to ensure the defects are adequately addressed.
  • Regression Testing: After defect resolution, regression testing is performed to ensure that the fixes have not introduced new defects and that existing functionality remains intact.
  • Test Closure: In the final phase, test closure activities are performed to formally conclude the testing process. Testers document test results, prepare test closure reports, capture lessons learned, and archive testing artifacts for future reference.

What is the Importance of Software Testing?

Before familiarizing you with the relevance and significance of testing in the entire software development process, let’s see how poor software testing have resulted in disastrous consequences:

  • Knight Capital Group Trading Loss (2012): A software glitch in Knight Capital’s trading algorithm caused the firm to make erroneous trades, resulting in a loss of over $400 million in just 45 minutes.
  • Healthcare.gov Launch (2013): The initial rollout of the U.S. government’s healthcare exchange website faced significant technical issues, including long loading times, system crashes, and difficulties with account creation and login. These problems stemmed from inadequate testing and scalability planning, leading to a chaotic launch and public outcry.
  • Heartbleed Bug (2014): It was a serious security vulnerability in the OpenSSL cryptography library and created an opportunity for attackers to access sensitive information, such as usernames, passwords, and private keys, from servers running vulnerable versions of OpenSSL.
  • WhatsApp Vulnerability (2019): A security vulnerability was discovered in the WhatsApp messaging app that allowed attackers to install spyware on users’ phones.
  • Zoom Bombing (2020): The video conferencing platform Zoom experienced a surge in popularity during the pandemic. However, users began experiencing hijacking of the session that were being marred with unauthorized accesses and improper content.
  • Log4j (2021): The critical vulnerability in the Log4j open-source logging library allowed attackers to exploit a feature that permitted the execution of custom code for formatting log messages. Using Log4Shell, hackers could remotely execute code on a target computer. The Log4j bug had far-reaching consequences, as it led to data theft, malware installation, and even complete system takeover, and impacted millions of computers globally.

Haphazard testing can have repercussions, as these incidents narrate. By serving as a bridge between development efforts and the delivery stage, software testing ascertains that software applications provide intended value. It is thus paramount to software development life cycle (SDLC) as it

Enables Early Defect Detection and Debugging

As Test-Driven Development encourages writing automated tests before writing the actual code, developers have a clear understanding of the expected behavior before implementation, and they produce a modular and testable code. TDD provides rapid feedback loops, allowing developers to catch defects at the earliest stage possible and maintain code integrity throughout the development process.

Carries out Error Detection and Debugging

Software testing involves executing the code with various inputs to uncover bugs and defects. Techniques such as unit testing, integration testing, and system testing help identify errors in different parts of the software. By detecting these errors early in the development cycle, developers can debug and fix them before they propagate into more complex issues that are harder to resolve.

Assists in Error Logging

Integrating error logging and monitoring mechanisms into the software allows developers to capture and analyze runtime errors, exceptions, and performance issues in real-time. Tools like logging frameworks, exception trackers, and application performance monitoring (APM) solutions provide insights into system health and help diagnose issues quickly.

Keeps possibilities in Code Changes alive

As software evolves with new features and updates, testing mechanisms such as regression tests keep the existing functionalities intact. Automated regression tests rerun previously executed tests to verify that recent code changes haven’t introduced unintended side effects or broken existing features. By continuously running regression tests as an integral part of the software development pipeline, developers confidently make changes without fear of regression issues.

Serves as a Continuous Monitoring and Feedback mechanism

Beyond the initial development phase, software testing extends into production through techniques like monitoring and A/B testing. Monitoring tools track system performance, error rates, and user interactions in real-time, and provide developers valuable insights into the software’s behavior in the live environment. On the other hand, A/B testing offers developers an environment to experiment with different versions of features or UI designs. Gathering the user feedback from these testing phases, they execute future iterations and improvements.

Is important for Localization and Internationalization

For software intended for global markets, testing for localization (adapting software for specific regions or languages) and internationalization (designing software to support multiple languages and cultural conventions) is critical. A professional software development agency implements localization testing and verifies that translated content and cultural adaptations are accurate and culturally appropriate. And next it implements internationalization testing to assure that the software architecture and codebase can handle diverse language and locale requirements without issues.

Optimizes User Experience

The application must be intuitive, easy to use, and meets user expectations. Usability testing and user acceptance testing (UAT) perform this task by focusing on assessing the software from the end-user’s perspective. With the help of quality assurance (QA) professionals and based on testing results, developers gather feedback from real users and bring out requisite improvements.

Helps build Inclusive Design

Testing must examine an application from an all-round perspective. For instance, the software must be usable by people with disabilities, including those with visual, auditory, motor, or cognitive impairments. This is what software testing processes like accessibility testing does. Techniques such as screen reader compatibility testing, keyboard navigation testing, and color contrast analysis help identify accessibility barriers.

Sustains Performance and Makes the application scalable

How the software behaves under various load conditions holds tremendous significance from the perspectives of scalability and long-term performance of the application. Performance tests allow the development team to examine how well the application can handle expected levels of traffic and user interactions without degradation in performance. Scalability testing further evaluates the software’s ability to scale resources efficiently as demand increases.

Provides Security Assurance

Testing software at different stages of development, right from initial design to post-deployment maintenance, make sure that security measures are integrated effectively and continuously. Moreover, testing serves as a mechanism for validating the efficacy of security controls such as encryption, access controls, and authentication mechanisms.

What are Different Types of Software Testing?

There are various software testing types, and these are applied to check the application from diverse angles. A software testing life cycle requires implementing different testing processes in combination. The following clusters offer a broad coverage of different types of testing processes.

Functional Testing

Functional testing validates that each function of the software application operates according to specified requirements. It verifies the behavior of individual software components or features by inputting data and determining if the output meets expected results. It covers the following testing types:

  • Unit Testing: Involves testing individual units or components of the software in isolation to validate their correctness, verifying that each unit performs as intended based on its specifications and requirements.
  • Integration Testing: Verifies the interaction between different modules or components of the software to make them function together seamlessly as a unified system.
  • System Testing: Evaluates the entire system’s functionality against specified requirements, testing its behavior as a whole so that it meets the desired outcomes.
  • Acceptance Testing: Involving stakeholders or end-users for validating that the software meets their expectations, this testing process checks if the system meets business needs and requirements.
  • Regression Testing: Confirms that recent changes or updates to the software have not adversely affected existing functionality, and that previously working features remain intact.
  • Smoke Testing: Conducts preliminary tests to verify basic functionality before more comprehensive testing, so that critical functions are ever operational.
  • User Acceptance Testing (UAT): As a type of end-users testing process, it validates whether the system meets the needs and expectations, and provides valuable feedback for any necessary adjustments or improvements.
  • Exploratory Testing: Simultaneously executes tasks such as learning, test design, and test execution, uncovering defects, usability issues, and potential edge cases.
  • Sanity Testing: Validates that the code changes have not introduced new defects and the important functions of the application work as desired.

Non-functional Testing

Unlike functional testing, which checks what the system does, non-functional testing assesses how well it performs under various conditions and if it meets quality standards set by stakeholders and industry best practices. Through the following testing processes, non-functional testing evaluates a system beyond its specific functionalities:

  • Performance Testing: Assesses the system’s speed, responsiveness, and scalability under varying conditions, such as different levels of user traffic or data volume, to identify potential bottlenecks and optimize performance.
  • Load Testing: Examines a system’s behavior when subjected to high levels of concurrent user activity or a heavy workload. So, you can determine if the system is able to handle a specific volume of users, transactions, or data.
  • Stress Testing: Assesses a system’s stability and reliability by pushing it beyond its normal operational limits. You can successfully identify the breaking point or failure modes of the system under extreme conditions, such as high loads, insufficient resources, or unexpected failures.
  • Usability Testing: Evaluates the user interface for its ease of use, intuitiveness, and user-friendliness, so that users can navigate the system efficiently and accomplish their tasks without any hassles.
  • Reliability Testing: Tests the system’s ability to perform consistently and reliably over time, detecting and addressing potential issues that could lead to system failures or downtime.
  • Security Testing: Identifies vulnerabilities within the system, keeping appropriate measures in place to protect against unauthorized access, data breaches, and other security threats.
  • Compatibility Testing: Checks the system’s compatibility with different environments, devices, and configurations, for smooth operation across various platforms and setups.
  • Scalability Testing: Evaluates the system’s ability to handle increasing loads and user demands without degradation in performance, so as to ascertain the system’s capability to accommodate growth without impacting user experience.
  • Localization Testing: Tests the software’s adaptability to different locales and cultures, so that it is properly translated and culturally appropriate for target audiences in specific regions.
  • Globalization Testing: Evaluates the software’s readiness for international markets, so that the application supports diverse languages, currencies, and cultural conventions, making it useful for diverse global audiences.
  • Recovery Testing: Validates the system’s ability to recover from failures or disasters, testing backup and recovery procedures and minimize downtime and data loss in the event of an incident.
  • Installation Testing: Verifies that the software can be installed, configured, and uninstalled correctly on various platforms and environments.
  • Interoperability Testing: Tests the software’s ability to interact and operate seamlessly with other systems, and that it is compatible and smoothly exchanges data in integrated environments.
  • Accessibility Testing: These testing procedures check if the application complies with accessibility standards such as WCAG (Web Content Accessibility Guidelines).

Maintenance Testing

Maintenance Testing is the process of systematically verifying and validating changes made to software systems, post initial development and deployment. It performs the critical task of validating that the modifications, enhancements, or updates maintain the desired level of functionality, reliability, and performance, while also detecting and rectifying any defects introduced during the maintenance phase. Maintenance testing framework will cover the implementation of these testing types:

  • Regression Testing: Verifies that recent changes or updates to the software have not adversely affected existing functionality, and also modifications made during maintenance do not introduce new defects or regressions into the system.
  • Configuration Testing: Often included in maintenance testing, especially when changes are made to the software’s configuration settings or environment, it validates that the software functions correctly under different configurations and settings.
  • Impact Analysis Testing: Assesses the potential impact of changes or updates to the software on related modules or functionalities, validating that the modifications do not cause unexpected side effects or issues elsewhere in the system.
  • Patch Testing: Tests patches or hotfixes applied to address specific issues or vulnerabilities in the software, so that the patches applied do not introduce new problems.
  • Version Testing: Tests different versions or releases of the software to validate changes and enhancements introduced in newer versions.
  • Data Migration Testing: Verifies the successful migration of data when transferring data between different systems or versions of the software, maintaining data integrity and accuracy after migration.
  • Backward Compatibility Testing: Keeps new versions compatible with previous versions of the software, so that users can upgrade without experiencing compatibility issues with existing data or integrations.

White-Box Testing

White-Box Testing is a technique of testing that scrutinizes the internal structure, logic, and code paths of the software application. Testers have access to the source code and design tests based on code analysis, check the completeness of code coverage and validate the accuracy of individual code segments, branches, and conditions. So, this testing methodology verifies the integrity of the software’s internal operations, uncovers potential errors and makes the code more robust. Following testing processes are performed as a part of white box testing:

  • Statement Coverage Testing: Checks if each statement in the code is executed at least once during testing and identifies unexecuted or dead code segments that may potentially harbor bugs or defects.
  • Decision Coverage Testing: Validates that each decision point in the code, such as if-else statements or switch cases, is executed with both true and false outcomes.
  • Condition Coverage Testing: Verifies that each condition in the code is tested with all possible combinations of true and false evaluations. So, this testing process uncovers errors or unexpected behaviors resulting from different combinations of conditions.
  • Code Coverage Testing: Code coverage encompasses various metrics such as statement coverage, decision coverage, and condition coverage to assess the extent to which the code is executed during testing. By providing insights into the thoroughness of the testing process, code coverage identifies areas of the code that may require additional testing.
  • Path Testing: Tests every possible path through the code, verifying the correctness of all code paths, and helps identify complex interactions between different code segments.
  • Mutation Testing: Evaluates the effectiveness of the test suite in detecting subtle bugs or defects introduced through code mutations i.e. small changes.

Black-Box Testing

Black Box Testing is a technique of testing in which the internal workings of the software are not known to the tester. Instead, the tester interacts with the software’s inputs and observes outputs, verifying that the software functions as expected based on its specifications. So, it scrutinizes functionality, interfaces, and external behavior, and uncovers errors and discrepancies without delving into the system’s implementation details.

  • Equivalence Partitioning: Divides input data into equivalence classes, testing representative values from each class to reduce redundancy.
  • Boundary Value Analysis: Tests inputs at the boundaries of allowed ranges to uncover defects related to boundary conditions.
  • State Transition Testing: Focuses on testing transitions between different states of the software, typically used for systems with finite states.
  • Decision Table Testing: Uses decision tables to test combinations of inputs and their corresponding outputs, covering all possible combinations.
  • Random Testing: Randomly selects inputs to test the software and detects unexpected behaviors or defects.
  • Cause-Effect Graphing: Analyzes cause-effect relationships between inputs and outputs to generate test cases, and thus contributes to comprehensive coverage.

What are the approaches to Software Testing

While those are the various testing methodologies that are performed during the QA process, they can be executed either manually or using automated tools. Going by names, we can infer about how the two approaches might be differing. Let’s understand, what they connote:

Manual testing

From exploring the software’s features, functionality, and user interface to identify defects or issues, following test cases and scripts, and performing ad-hoc testing to find unexpected behavior, everything is done manually.

Automated Testing

Involves use of specialized software tools to execute test cases and compare actual outcomes with expected outcomes automatically, and testers write test scripts to automate the testing process. This approach is particularly useful for repetitive tasks such as regression testing, load testing, and performance testing.

What are the Best practices for Implementing Software Testing?

You may have a great quality assurance (QA) team, a great infrastructure and tools. However, for successful results, it must follow these best practices for implementing software testing in the SDLC.

Have Clear Requirements and Measurable Objectives

Begin testing with a clear understanding of project goals and requirements, utilizing the Software Requirement Specification document for insights. Set objectives for testing, defining what needs to be tested and establishing the scope of testing efforts to ensure effective evaluation of software quality and functionality.

Combine Different Testing Types

Ensure thorough evaluation by incorporating various testing types, including functional and non-functional testing. By verifying both intended functionality and aspects like performance and security, teams can enhance the software’s resilience and reliability across diverse scenarios.

Integrate testing in the development stage

Optimize software quality by embedding testing processes within the development lifecycle, leveraging Continuous Integration/Continuous Deployment (CI/CD) Pipelines. Early integration facilitates rapid feedback loops, enabling timely bug identification and iterative refinement of software features.

Make sure that development is test-oriented / TestDriven development

Cultivate a test-centric development culture through methodologies like Test-driven Development (TDD) and Pair Programming. Through test creation and code refinement, developers proactively mitigate bugs, and make the code more robust and maintainable.

Test one feature per case

Isolate individual software features for bug detection and precise validation of feature functionality. When you create a test case for independent features you promote the potential reuse of the case in multiple tests or integration scenarios.

Report Bugs Effectively

Include information such as steps to reproduce the issue, expected behavior, and actual behavior in software bug reports, so as to enable developers to quickly identify and address the root cause of the bug. The bug report must exhibit clarity so that each member of the quality assurance (QA) team is able to infer the insights. A professional software development agency will always use tools such as Jira, Bugzilla, Mantis Bug Tracker etc. to report bugs.

Involve Non-Testers in Testing Efforts

Developers bring their own experience and knowledge which must be effectively used in the testing process. As a result, developers, product managers, and the testing team must collaborate as the former two offer insights into user requirements and expectations that will always be deciding elements in the testing process.

Ensure Comprehensive Coverage

Minimize the risk of undetected bugs and vulnerabilities by conducting comprehensive testing across all aspects of the software. Comprehensive testing includes functional testing to verify that the software meets user requirements, non-functional testing to evaluate performance and security, and regression testing to ensure that new changes do not introduce new defects.

Invest in a Secured Testing Environment

Protect sensitive data and ensure the integrity of testing processes by investing in a secure testing environment. Implement measures such as access controls, encryption, and secure network configurations to prevent unauthorized access and data breaches during testing.

Use Automation Testing Wisely

Leverage automation for regression testing, so as to check that new changes due to repetitive tests don’t introduce bugs. Additionally, it’s effective for smoke testing for validating basic functionality works after changes. Yet, complex scenarios and exploratory testing are better suited for manual testing, as automation may miss nuanced issues.

Implement a two-tier testing framework

A two-tier testing framework combines automated and manual testing to optimize testing efforts. In this approach, automated testing handles repetitive and critical path tests, while manual testing focuses on exploratory testing, edge cases, and scenarios that require human intuition and creativity.

Manage Testing Using a Test Management Platform

Employ a robust test management platform to streamline testing processes and enhance collaboration. These platforms offer features such as test case management, requirements traceability, and defect tracking that centralize testing artifacts and integration with other tools like bug trackers and automation frameworks.

Use metrics-based monitoring

Monitor testing progress and effectiveness by tracking key metrics such as test coverage, defect density, and test execution trends. Use test management tools to collect and analyze this data and regularly review these metrics to track progress, identify trends, and pinpoint areas requiring improvement, adjusting testing strategies accordingly.

Implement Negative Testing

Deliberately input invalid data or perform actions that are not expected, which is one great way to allow testers to identify potential vulnerabilities and edge cases that may not be addressed through traditional testing methods.

Implement exploratory and ad hoc testing

Uncover unforeseen defects and usability issues by complementing structured testing methodologies with exploratory and ad hoc testing. Through exploratory testing, you will explore the software in an unscripted manner and would be able to identify defects and usability issues, while through ad hoc testing, you will be able to test without predefined test cases and uncover defects that may not be identified through traditional testing techniques.

What are Different Types of Software Testing Tools?

Test Management TestRail Comprehensive test case management tool with reporting and analytics features.
HP ALM (Quality Center) Enterprise-level test management tool with requirements management and defect tracking.
Zephyr Dynamic Test management solution integrated with Jira for agile teams.
Bug Tracking Jira Issue tracking tool with agile project management capabilities.
Bugzilla Open-source bug tracking system with customizable workflows.
MantisBT Web-based bug tracking system featuring collaboration and custom fields.
Automated Testing Selenium Open-source tool for automating web browsers across various platforms.
Appium Open-source tool for automating mobile applications on iOS, Android, and Windows platforms.
Ranorex Test automation tool for desktop, web, and mobile applications.
Performance Testing JMeter Open-source tool for performance and load testing of web applications.
LoadRunner Performance testing tool for simulating thousands of users to measure system performance.
Apache Benchmark Command-line tool for benchmarking HTTP servers by generating requests.
Security Testing OWASP ZAP Open-source web application security scanner to identify vulnerabilities.
Burp Suite Integrated platform for performing security testing of web applications.
Nessus Vulnerability assessment tool for identifying security weaknesses in networks and systems.
Static Analysis SonarQube Open-source platform for continuous inspection of code quality to detect bugs and vulnerabilities.
ESLint Pluggable linting utility for JavaScript code.
FindBugs Open-source static analysis tool for identifying bugs in Java code.

To Wrap Up

We covered the length and breadth of software testing and that will prove valuable in your testing process. However, we just offered the theoretical idea of the concept, and in the practical process, you might encounter issues that would require taking contextual decisions.

Software testing is a highly technical process, where technical depth, skills, and perfection of documentation culminate to successfully take a software through a rigorous checking mechanism.

You can build and test your products from our experts who bring rich experience in handling these complexities. To start, get insights today.

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