Every software project begins with an SRS (Software Requirements Specification Document) that contains, among others, the functional requirements of the project. In simple terms, this document captures in ‘layman’s language’ what the customer expects the software to perform. Unfortunately, there are cases when clients’ expectations are not met. This is the gap where functional testing can provide assistance.
Testers seek to establish whether or not the functionalities in the software are performed accurately using functional testing. In this blog, we will discuss everything related to functional testing, its types, examples, procedures to execute it, and much more.
Functional testing, or specification testing, verifies if the functions of an application operate in accordance with the business processes captured from the users or stakeholders.
This test focuses on the software’s functionalities and ensures that complete internal code structure or implementation details do not matter.
Functional testing is subset into two bases: requirements and business.
Requirements-based functional testing inspects the provided functionality of the software system with the documentation complete with specific provided details having relevant test cases based on documentation known as requirement files. For example if mentioned in requirement document that in login screen user name length should not be more than 20 characters. So we need to make sure when we will test our actual result must meets the expected result as mentioend in requirement document.
Business scenarios-based functional testing assesses the software system in the context of techniques for the business and completes the test with test cases based on actual business requirements.
Within the sequence of testing, functional testing takes place after unit testing and precedes non-functional testing. It is performed by QA testers. Below are the activities performed during the functional testing stage:
Verifies that system functions are reached by all users using the interface as they should
Validation of system errors that the software has on diagnostics of the modules executed
Emphasizes the critical actions associated with the software to establish their operational status.
Confirm the functional usability of the software in such a way that users will not experience difficulty interacting with the software.
Non Functional Testing focuses more on performance, usability, and other application traits as opposed to its core features. It tests if the software complies with its quality settings like speed, security, and scalability.
Non functional traits encompasses everything that have not been verified through functional tests therefore in non functional testing everything not previously checked by functional tests will be investigated.
Some elements of non-functional include performance and usability, flexibility, stability and non-functional aspects can sometimes be included if deemed necessary by the project scope. Just as in functional tests, in this type of QA verification, SRS (Software Requirements Specification) documents are also used to develop test scenarios, suites, and scripts.
The aim is to enhance the overall non-functional parameters so that the software being tested can provide an optimal user experience.
Scope of Non Functional Testing
Finding gaps in software maintainability and usability, effectiveness, stability, and portability.
Mitigating the chances of bugs, user discontent, and financial loss occurring during production when the software is exposed to real end-users.
Making debugging easier and simplifying the installation, configuration, management, and monitoring of the software.
Identifying, based on anticipated real-life use, the metrics that need scrutiny to evaluate the success of the product.
Contributing to existing repositories of knowledge, whether internal or open-source, regarding the product and the technology underlying it.
Categories of Non Functional Testing
1. Testing Effectiveness / Performance Testing
Evaluates if software works on the optimal threshold.
Looks at the spent time and expense relative to loading time, crashing frequency, memory, latency time, throughput, and CPU interrupts per second.
Pro tip: For automated performance testing of mobile apps, use BrowserStack App Automate and for analyzing and optimizing page load speed, use SpeedLab for enhanced web performance.
2. Load testing
Checks how a system handles an increased load, say multiple user logins or transactions happening simultaneously.
Evaluated under stressed conditions to ensure stability and scalability.
3. Security Testing
Determines the exploitable weaknesses and vulnerabilities within the software by thinking like a hacker.
Looks into system design to storages that could be broken into for information and unauthorized changes to the data.
Various tools aid organizations in carrying out functional testing. These include:
Selenium: this is an open-source program that assists in automating web browsers including support of different programming languages, both JUnit and Test NG, and a wide range of browsers.
QuickTest Professional (QTP)/ Unified Functional Testing (UFT): possesses keyword and scripting interface capabilities, Micro Focus’s functional testing tool enables integration with ALM along with supporting different environments such as web, desktop and mobile applications.
JUnit: this is a Java web application testing framework that supports automation for tests as well as TDD which allows the use of Maven and Gradle for integration, Provides annotations for each of the test methods.
TestComplete: offers script and no-script options with support of various scripting languages, object recognition and image-based testing, SmartBear’s TestComplete is a commercial application that caters for desktop, web and mobile testing.
Ranorex: supports mobile, web, and desktop applications UI test automation. The application permits automation without programming through capture and replay, detailed reporting, and analysis, as well as the integration of CI/CD tools such as Jenkins and Azure DevOps.
Appium: this open-source program that specializes in mobile application automation is capable of cross-platform testing for iOS and Android, as wellas supporting native, hybrid and mobile web applications.
Cypress: test automation becomes easier due to real-time debugging and an intuitive API offered by Cypress, making the program renowned for simplicity and robustness.
Playwright: developed by Microsoft, the cross-browser tool has gained popularity for enabling developers to effortlessly automate tests across different browsers and devices.
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When considering a tool for functional testing for your project, remember to consider the following questions:
What relative compatibility does the tool have?
Can the tool be categorized as user friendly? What is its learning curve like? For instance, if there are team members who do not have the slightest idea of the scripting language, is there a possibility of translation to other languages?
Is automation supported?
Will it accept integration with other tools and frameworks? For example, can test scripts developed on one operating system be executed on other operating systems?
What are the licensing terms that apply to the tool?
Functional testing involves verifying a system against its functional requirements, including the relevant use cases delineated in the test matrices.
Testing can be classified into two primary categories: functional and non-functional types of testing. The first category examines the functionality of an application, software, or system, whereas the second category scrutinizes the non-functional components such as security, performance, and compatibility.
In the absence of a system’s functional requirements, one cannot perform functional testing because there are no definitive functions or behaviors that the system is supposed to exhibit.
A functional requirement is a type of project specification or documentation that outlines the said functions, tasks, or actions expected out of a system or a product. They delineate what capabilities and features ought to be there in the system currently under development. Functional requirements are usually narratively captured through system operations, user actions such as user stories, or interactions among system components. Therefore, functional requirements may look like this:
The ‘add’ function must take two numbers as arguments and yield their sum as the output.
User registration: The system has to allow users to register by filling in and submitting their personal details.
Adding items to the cart: In an online store, it should be possible for users to add items to their shopping cart by clicking on the ‘Add to Cart’ button.
The main objective of functional testing is to ensure compliance to system requirements given in the system documentation.
An auxiliary aim of functional testing is to locate functional bugs. It is, however, necessary to mention that bug fixing should never be the primary focus of functional testing. In the first place, functional testing is performed to raise confidence about quality and verify the product or system is working as designed.
In most cases, these practitioners are called QA engineers. Functional testing is usually done by testing specialists or by developers during the unit test phase. In test design, a commonly accepted principle is that the tester needs not be the product developer.
The step of functional testing starts with requirement collection and is tailored towards the defined objectives of the client. As is usual, the client provided requirements are high level which basic system analysis usually quotes as “As a User, I would like to log into my account and view my personal dashboard”.
This information may not be sufficient for the QA team that has to perform the functional testing. In these scenarios testers need to be able to interact with the users to analyze the requirements and address the problems within the scope of the client requirements and make sure that all the features are properly implemented as intended.
This can be done in the most simplest manner by considering user stories as large narratives and subdividing them into applicable smaller fragments to solve specific problems. You must write comprehensive test cases for every individual chunk that streams out the functionality verification. Using the above example, starting with the aforementioned request, here is a clear example of how you can deconstruct it:
Scenario: A user wants to transfer the funds from his savings account into his current account using an online banking platform.
To define the functional tests for the above mentioned scenario, you have to:
Review all potential inputs like letters, numbers and special characters. Your assertions should aim to check functionality.
Conduct the tests selected, either by manual testing or using automated techniques.
Verify the outputs, for example, messages or alerts confirming successful transfer “Successfully transferred”.
Various techniques of functional testing can be employed to validate the above scenario:
System tests
System tests focus on verifying that all system components are functioning correctly and in conjunction with one another. Continuing with the above example, a solution would be checking if the user can open the online banking platform, log into the online banking application, go to “Transfer Funds”, fill out the amount to be transferred, select the accounts to be debited and credited, and execute the transaction.
Expected result: The transaction will be completed, the balances in the accounts will be updated accordingly and the appropriate funds will be debited from the savings account and credited into the current account.
Equivalence tests
Test data are grouped into classes with the help of classfication tree methods and the reasoned assumption ship testing model.
These partitions are referred to as equivalence test cases. With an equivalence test, you can check if the data in every partition responds in the same way. Therefore, at satisfactory condition, you will get the anticipated results upon testing one condition in all partitions. Also, if the condition is not working in one partition, it will not work in any of them. In the above example, you can test the funds transfer from the balance of $100, $500, and $1000.
Expected outcome: Successful transfer of funds for all cases tested including multiple transaction scenarios.
Boundary value tests.
If there are certain data limits that the user cannot reach, Boundary value tests are intended to verify how the system behaves. In the example, the values of $0, $1, $9999, and $10000 are transfer tested.
Expected outcome: Transaction of either negative value or $0 should be denied.
Decision based tests.
This test enables you to analyze how the system operates when the user has satisfied some requirements. For instance, what occurs when he attempts to transfer funds between different types of accounts or enters incorrect account credentials?
Expected outcome:
A user receives a message “Invalid credentials” upon entering incorrect credentials.
He receives a notification stating “Transaction Successful” post the successful transfer of an amount.
A fee applies for transferring funds between different accounts.
Establishing discounts for holders of a premium class account.
Ad-hoc tests.
Ad-hoc tests are conducted around issues that other tests will not address. For example, at the ad-hoc level, you may test transferring funds with a user who is simultaneously logged in from different devices, entering different invalid amounts or account numbers, and leaving the transfer page to return at a later point to complete the transaction.
Expected behavior: Any issues that were not anticipated, such as inappropriate handling of active transactions, out of business validation checks for invalid inputs, and inconsistencies within the system throughout the transfer stages, will be resolved.
The Effect of Functional Testing on User Experience
A functional test will confirm whether each element of an application is working optimally, which subsequently enhances user experience since all software functions work as they should. If the features operate as expected, there are minimal obstacles within user navigation, reducing the risk of errors. Testing aids in the resolution of bugs, resulting in a dependable and trustworthy application, thereby improving users’ satisfaction.
Aside from improved dependability and user satisfaction, a functional test bolsters system efficiency and security.
Making sure that the application is working properly and that user data is kept private enhances user experience for safety as well as enjoyment. Users become more satisifed as they are confident that the software will function properly and their data will be kept private.
Best Practices for Functional Testing
This section provides some of the best practices that can be implemented when conducting functional testing.
Creating Effective Test Cases
Test cases should always be written in a manner that is straightforward so that others can understand the language used. The test cases must also be detailed enough to include steps for execution and specific outcomes. Moreover, impact from the users as well as critical functionalities must be taken into consideration in setting the priorities of the steps. In addition, it is important to mention that each test case is bound to certain requirements.
Additional Read; How to write test cases for an e-commerce website?
Test Data Management
There are certain standards and policies that must be followed when dealing with creating and managing test data and you must apply the same during the entire process. For easy reference, you may choose to have a separate repository that stores data that can be reused. For collection of used data, company policies and data privacy regulations set forth must be adhered to when dealing with test data. These policies can easily be followed by frequent auditing and reviewing policies concerned with handling of test data.
Test Environment Configuration
In order to carry out functional tests, having a set of guides will serve as useful tools and they must be documented and versioned.
Virtual machines and containers allow for quick replication of differing environments. You should consistently maintain and update the testing environments to prevent any inconsistencies.
***Integration of Testing with CI***
Automate the execution of functional tests through CI/CD pipelines to implement continuous testing. It allows for early identification and resolution of bugs. Immediate feedback further enhances the developer’s experience and accelerates the overall development process.
Changes or incomplete requirements may result in gaps in test coverage and lead to confusion among testers regarding what needs validation. By interacting with project stakeholders, which include developers, business analysts, and product owners, you can resolve requirements and modification issues.
Requirement changes can be disruptive to the testing process, requiring continual changes to test cases, and may cause some tests to go incomplete, yielding unexploited defects and missing out on fully functioning tests. One way to resolve this is to implement agile methodologies by subdividing the project into smaller work units (sprints) which are completed with regular milestones.
Testing modern software often entails multitudes of systems and third-party components. Assessing these integrations for proper functionality, data transfer, and compatibility may be very intricate and exhaustive. Repetitive and regression testing automation will enable the testers to capture more intricate scenarios and perform exploratory testing. You can also adopt integration testing with advanced testing tools and frameworks that support automated processes.
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