The ultimate guide to functional and non-functional testing

The ultimate guide to functional and non-functional testing

One sort of software testing is called functional testing, and its purpose is to validate the software system about the functional requirements and specifications. Functional testing aims to validate each function of a software programme by simulating its use with the relevant data and then comparing the results to the specifications outlined for that functionality. Black box testing is the primary component of functional testing, and this type of testing does not care about the application’s source code. The User Interface, Application Programming Interfaces (APIs), Database, Security, Client-Server Communication, and other functionalities of the Application Under Test are all tested during this testing phase. Testing can be done by hand or automatically using whichever method is preferred.

Simply put, it is a testing type that ensures each software application‘s function is working correctly under the requirements and specifications. The testing in question is not concerned with the application’s source code. The software application’s many features are put through their paces by being placed through proper testing input, anticipating the anticipated outcome, and then contrasting the actual output with the expected output.

Different kinds of functional testing:  

Different kinds of functional testing:

  • Checking for Sanity:

This is typically done after smoke testing and is used to verify that each central capability of an application works correctly, both on its own and in conjunction with other components. This testing is called integration testing.

  • Usability Testing:

When the product is put through its paces in a setting similar to production, it is evaluated by an actual customer. The needs of the user are catered to, and their opinions are considered. This is analogous to vetting prospective users for admission.

  • Testing the Integration of:

Integration testing is performed when a system’s functionality depends on the simultaneous operation of many functional modules. This testing verifies that the individual modules perform as intended when used in conjunction. This verifies that the system, from beginning to end, produces results up to the required requirements.

  • The testing of regression:

This test verifies that any modifications made to the codebase (new code, debugging strategies, etc.) do not disrupt any of the functionalities that are currently in place or cause any instability.

  • Beta/ Usability Testing:

At this point, the product is put through its paces in a production setting by actual paying consumers. At this stage, it is vital to determine the degree to which a consumer is comfortable with the interface. Their suggestions are taken into consideration when creating additional code changes.

  • Smoke Testing:

After the completion of each build, this step is carried out to check that the software’s consistency has been maintained and that it has not encountered any anomalies.

Standard Procedures for Functional Testing Are As Follows:

The following order should often be followed when developing a plan for functional testing:

  • Determine the Objectives of the Tests:

The aims of functional testing are the features that the software is anticipated to possess by the project’s requirements. Validating that the programme functions as it was designed to and ensuring that it responds appropriately to faults and unforeseen circumstances are both important testing goals.

  • Create Test Scenarios:

Create a list of all the available test scenarios (or at least all the essential ones) for the function being evaluated. Test scenarios are used to explain the many functions that the feature will perform. For example, the test cases for a module that processes payments might include the processing of numerous currencies, the management of invalid or expired card numbers, and the production of a notification upon successful transaction completion.

  • Create Test Data:

Construct test data based on the test scenarios you defined that represent everyday use situations. You can enter test data manually (for example, from a spreadsheet created in Microsoft Excel or a printout) or automatically through a script or testing tool that reads and inserts the data from a database, flat file, XML, or spreadsheet. Each collection of data used as input should also have associated data that describes the expected result that the data will produce.

  • Develop Use Cases for Testing:

Develop test cases based on the many outputs and inputs you want the test to produce. For instance, the application should present a clear and informative error message if the user enters an incorrect credit card number.

  • Carry out the Test Scenarios:

Execute the test cases using the application, and then examine the difference between the actual and predicted results. The feature is considered to have failed the test, and a fault should be filed if the actual outputs and expected outputs do not match.

  • Defects Should Be Focused On, Tracked, and Resolved:

After a flaw has been located, its details should be entered into a formal tracking system to which every project team member has Access. Before a defect is recognized as resolved and closed, the necessary modifications should be made to the application, and the test case should be rerun.

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Functional Testing Characteristics and Features:

The automation of the guide’s repeated sections and the flexibility and filtering of the guide’s results are both made easier thanks to solutions like Test Complete, which automate these functions. In addition to that, the provision of Test Complete improves its function. Even the most basic functional test ought to be relevant throughout a project so that outcomes may be automatically compared against a standard output that was previously certified. As a result, its status outside the application should be preserved to the greatest extent possible.

TestComplete possesses all of the necessary qualities to satisfy this requirement, including the following:

  • Tests and scripts that use any programming structure in your tests have graphically designed loops; if the conditions are then, catch blocks, remarks, and so on.
  • Specific technologies and methodologies, such as Windows formats, Developer Express, Syncfusion, Qt, Infragistics, Telerik, MFC, and so on, can be utilized to test third-party control applications thoroughly.
  • Test Complete provides unequalled Access to internal properties and application approaches, enabling users to perform a more in-depth level of functional testing.
  • It is the responsibility of the developers to ensure that testing is performed on the specific code that is relevant to them. This presents a problem that could arise. On the one hand, it ought to function independently of the programme, while on the other, the application ought to scrutinize its internal components.
  • To fix this potential problem, TestComplete can Access the application’s internal information and retrieve the necessary data.

The following are some advantages of functional testing:

It is to everyone’s advantage to supply the end users with effective and dependable application software. The following is a list of the many benefits that functional testing brings to companies and business organizations.

  • The guidelines’ requirements for end-users serve as the primary focus of functional testing, which then tests the various models of the applications.
  • It allows for testing reports to be created using accurate facts and numbers.
  • This kind of testing is carried out when the product is very near to being delivered to users, such as an operating system, browser, or database. Excel
  • It is a testing method that focuses on the company and helps to narrow the gap between the business organization and the applications of the product or service being tested.

Functional testing has the following disadvantages:

  • Because it is common knowledge that everything has both positive and negative aspects, it should be no surprise that functional testing also has a few drawbacks, some of which are described in more detail below.
  • It is a process in which numerous logical errors in the programme are not noticed during the testing process. This can happen in several different ways.
  • When there is also a chance of duplicate testing, which puts the testing expense and efforts in my hands, where is the possibility of redundant testing?
  • Because it is solely concerned with the outcomes of the source code, it doesn’t care how the developer puts the source code into action; all that matters is the result.

What exactly does “Non-Functional Testing” entail?

One kind of software testing is called non-functional testing, and its purpose is to ensure that an application satisfies specific criteria unrelated to its functionality. It examines the system’s behaviour to determine whether or not it conforms to the requirements. It examines all of the facets, including those that are not examined in functional testing.

Non-functional testing is a subcategory of software testing that examines a program’s components that are not directly related to its functionality. Its purpose is to evaluate whether or not a system is ready to operate based on nonfunctional factors, which are never considered in the context of functional testing. Testing for non-functional aspects is just as vital as testing for functional aspects.

The following are examples of non-functional testing types:

  • Evaluations of Performance:

Testing for performance examines how effectively individual software components function. These tests identify problems with the design and performance of the software architecture.

In most cases, this is accomplished by:

  • Timing the responses to stimuli
  • Identifying bottlenecks
  • Locating failure points

Tests of the software’s performance confirm its quality. They ensure that it is quick, scalable, dependable, and stable in its operation.

  • Availability testing:

You need to conduct tests to determine how frequently the product will be utilized and whether or not it will be accessible whenever the users require it. For instance, you want to reduce the number of instances of the system failing or estimate how much time it will take to repair until the system returns to its normal state.

  • Examination for compliance:

Checks to see if a mobile application complies with rules or regulations.

  • Examination of the localization:

Testing the product at a local level ensures that it lives up to the standards of the target demographic in that area. If you want to localize a mobile app that was initially built for the United States market for the Chinese market and translate it into Chinese, for instance, you will need to use this kind of testing.

  • Examination of scalability:

The software testing technique known as scalability testing ensures that the product can grow in proportion to the rising needs of the end-users. Scalability testing ensures that the product can grow in proportion to the increasing demands of the end-users.

  • Evaluation of dependability:

This testing technique for software combines stress testing with functionality testing and security testing, indicating whether or not the software product meets the standards for functionality.

  • Examination of the security:

The tester looks for weak spots in the system and evaluates the level of security afforded to sensitive information and internal resources.

  • Testing under load :

To guarantee the consumers an interoperable performance, it is necessary to understand how the programme will act when subjected to a specific load. Testing your system under a heavy load allows you to evaluate its performance under extreme conditions.

  • The endurance test consists of:

This kind of testing aims to determine how well software functions when subjected to heavy loads. Nevertheless, the load keeps getting heavier and heavier over a protracted period.

  • Examination for compliance:

This software testing ensures that the product satisfies international standards for software production. Multinational corporations typically formulate these standards. For example, a mobile application needs to meet the App Store’s or Google Play’s requirements to be distributed there.

  • Examining under pressure:

Tests of this kind are carried out to determine how a programme fares when subjected to various loads and stresses that affect its functionality.

  • Maintainability testing:

It is essential for software to have the capacity to make it through modifications and upgrades without crashing. Testing for maintainability evaluates how well a system can adapt to changing circumstances.

  • Examination of transportability:

The ease with which a software component or application can be moved from one piece of hardware or operating system to another is determined by this factor.

  • Tests of the disaster recovery system:

After a system failure or an interruption in network connectivity, this testing is carried out to determine how long it takes to recover and how successfully the software can retrieve lost data.

Non-functional testing has the following advantages:

There are many advantages to doing a non-functional test, some of which are listed below:

  • The functionality of the application is enhanced as a result. Ensures that the application can support many users at once without experiencing any loading problems and continues to function normally and effectively.
  • The application’s level of safety is increased as a result. Provides security against unauthorized Access to the application.
  • It encompasses testing that isn’t possible in functional testing, or that isn’t covered by it.

Non-functional testing has the following disadvantages:

The following is a list of some of the drawbacks associated with testing that is not functional:

  • Every time an update is made to the software, it is imperative that the non-functional tests be rerun.
  • Due to software upgrades, users are required to pay to reevaluate the software, which makes the cost excessively high.

Comparing Functional Testing with Other Types of Testing:

Functional Testing:

  • It evaluates ‘What’ the product is capable of doing. It examines the processes and behaviours that an Application is performing.
  • The functional testing that is performed is based on the requirements of the business.
  • It examines the actual result to see whether it functions according to the expected result.
  • This process is carried out by hand. For illustration, the black box testing approach.
  • It validates the specifications provided by the client.
  • The comments and suggestions of customers are valuable in lowering the product’s inherent dangers.
  • The functioning of the software is being tested at this time.

Testing that is Non functional:

  • It examines how an Application behaves.
  • Testing that is not functional is carried out by the customer’s performance requirements and expectations.
  • It examines how long it takes the software to respond and how quickly it operates under specific scenarios.
  • The use of automated testing technologies makes testing more practicable. Example: Loadrunner.
  • It passes the tests as expected by the customer.
  • Feedback from customers is constructive for non-functional testing because it contributes to the improvement process and informs the tester about the consumer’s expectations.
  • It evaluates how well the software’s functionality performs under various conditions.


Functional testing is subject to a wide variety of potential theoretical and practical constraints, some of which may or may not exist. Few theories hold that functional testing is a vital component of the testing process, even though some cast it in a negative light. Maintaining the application’s adaptability should be a priority if you want to get the most out of your efforts to perform functional testing. This requires you to map the functions of the business requirements to the individual tests. Functional testing shouldn’t ever be the only testing that a test engineer does. Because there are additional facets that need to be examined before supplying the software to the end users, such as non-functional testing, go to the end users.

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