Best Practices for Functional Testing | Global App Testing

Functional tests are designed to show that your product works to specification. This guide will tell you what that means in more detail, and how to plan and execute functional tests well – everything from selecting the best possible functional test breakdown to undertaking a range of products and services in functional testing.


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Table of contents

This article will cover:

  1. What is functional testing? Definitions, disambiguations, and more
  2. Best practices for functional testing 
  3. Tools and services for functional testing

Skip to tools & services


Recap | What is functional testing?

Functional software testing is any type of software testing that focuses on verifying the system behaves to specification.

Much of functional testing is built around “test cases” – scripts which describe the intended result of taking an action in a piece of software based on the software documentation. Testers are asked to take the described action and verify that the result is the intended result. 


How is functional testing different from non-functional testing? 

Non-functional testing is designed to cover attributes of a system not covered by functional tests, while still finding measurable outcomes. 

Non-functional testing might include: 

  • performance testing
  • reliability testing
  • load testing
  • Some kinds of usability testing.

 A UX survey would not be either functional or non-functional test, but we would describe it as a kind of user test on this website. 

This website describes further kinds of tests which count as neither functional nor non-functional; including localization testing and accessibility testing. In reality, some tests within l10n or a11y categories arguably overlap functional / non-functional, but we are following a convention to keep the test categories distinct. As with much in QA, the taxonomy of testing can be woolly and poorly defined.


Types of functional tests 


Functional testing is more than just execution; there is much complexity in terms of the test management and overall QA planning and QA processes. Below are different types of test execution.

A) Test cases vs exploratory tests

The bulk of most functional testing is from test cases which are described above: they are scripts of steps with an expected outcome specified for every step.

We would also recommend exploratory testing, tests which ask testers to find bugs without scripts or test cases, but by using examples of bugs which are critical and inviting them to play with and explore the software. These complement test cases which may miss edge cases, or critical areas where bugs can build. 


B) Automated vs manual functional testing 

We’ve written a blog recommending how to identify whether a QA test should be automated or manual.

To what extent a QA team should automate its functional tests depends on factors which include: (i) how often the test will be reused; (ii) how easy it is to automate the test; (iii) the likelihood that automated test may flake (e.g. due to a changing product) – etcetera.

Many of our clients pursue automation-first testing approaches and use Global App Testing to manage their supply of QA labour flexibly and effectively to support that automation. Or to handle tests which just for now, can’t be automated.


C) Regression functional testing vs release testing 

Regression testing focuses on verifying that the existing functionality of a software application remains unaffected after new changes or updates have been introduced. A business will typically have a series of different regression test case scripts which we spell out in this article.

Release testing, also known as release validation or pre-production testing, is performed to validate a software application before it is released to end-users. It is a critical step in the software development lifecycle.

With Global App Testing, you can identify your build stage (from prototype through to live product) and execute test cases or exploratory tests on any of them.


D) Version and compatibility testing 

Version and compatibility testing in software testing has the aim of ensuring that your software works well with different versions (e.g. 1.1, 1.2, etcetera) and different environments of other kinds – including OS systems, browsers, platforms, devices, or any other kind of device. Managing devices and versions and geographies is very difficult to do in-house, and is one natural advantage that outsourced QA providers accrue over in-house teams. 


E) Reproducibility testing and bug fix verification

Re-testing and bug fix verification are what they sound like. Reproducibility retesting is sometimes performed to understand the extent of a problem – when a bug is discovered, you may wish to immediately test it again in another production environment to see what’s happening there (i.e. is this a version thing, or does this result remain true in every device and OS?).

A bug fix verification would be to ensure that once you’ve fixed the bug, the application is again working to specification.  Our test launch platform allows you to immediately retest software straight from the results view. 


F) Other well-known functional test “types”: smoke, unit, integration

Some kinds of functional test are also worth mentioning but are nonexclusive with the above tests and are worth mentioning here: 

Smoke testing is a common sense test which takes place at the start of a testing suite, to verify whether the application works in a broad sense and that it’s sensible to continue testing. It’s a broad-but-shallow test of many parts of the system to ask “is it broken?” A smoke test is a common part of a regression test suite, for example. 

The"unit" in "unit testing" refers to the smallest testable component of a software application. It typically refers to a single function, method, or procedure in the codebase. The idea is to isolate as small a code area as possible for review. The extreme end would be “system testing” which tests the entire software system end-to-end and is a common last step procedure.

Hardware testing, which is available for IoT products via Global App Testing, requires some kind of physical test which cannot be done through an emulator. Practically, this may include sending and receiving signals: bluetooth, LIDAR, laser, sound, and other physical product attributes.

Integration tests test integrations: in addition to being a common failure point this can also be more complicated to automate and run in an emulator because it may involve software from outside your system.


G) Specialist industry testing 

Some software categories such as payments and gaming require specialist techniques and feedback styles which are good things to look out for when you are planning a software test. These include payments and blockchain, gaming, and AI. 

Most of the above test “types” are non-exclusive – you could have an automated compatibility test case set as part of your total regression testing suite, for example. 


Chat with a QA expert 


What kind of functional testing should I be doing?


Read our full article about QA planning.

The specifics of a functional testing strategy can vary depending on the nature of the business and the software being developed. Here are some best practice notes we’d like to share which we feel are broadly applicable across businesses:

  • Businesses typically automate less than they expect (or integration partner TestRail made this observation based on their annual survey – that businesses seem to systematically overestimate the % of tests they would able to automate the following, thinking they would automate 20% more. On average, they automated about 1% more. A separate survey found that a high proportion of flaked tests was the most common reason for not fulfilling expectations.

  • We’d argue that accessing flexible tester supply through Global App Testing is one answer for this uncertainty; providing the ability to scale and reduce manual testing to fit requirements on the day.

  • Exploratory tests are generally more cost effective to find bugs after a certain point and often overlooked by businesses.

  • Prioritizing test cases can be done based on likelihood of bug; severity of bug (e.g. legal and safety areas should come first); random test case priority or revolving test case priority to cover an entire system over time.

  • Solid test management software more than pays for itself in terms of reducing wasted time.

  • Regression testing is likely to be the bulk of your testing effort, so pay close attention to the operations and expense associated with it.

  • It’s easy to forget that QA is a business function which relates to business goals. Great leadership through clear objectives and frameworks will be felt throughout your quality process; particularly in how and why you test live products to find improvement areas. 

If you do not know where to start, you can easily find a framework similar to the below: 

Requirements Analysis > Test Planning > Test Case Design > Execution > Defect reporting. 

Devise a process for each one which reflects your strategy (below).



Different industries tend to have different priorities, for example: 

  • E-commerce: The testing strategy may focus on product search, shopping cart functionality, payment processing, and order management.

  • Banking and Finance: Testing would include verifying account management, transaction processing, security measures, and compliance with financial regulations.

  • Healthcare: The strategy might involve testing patient records management, appointment scheduling, billing systems, and integration with medical devices.

  • Gaming: Testing would cover gameplay mechanics, user interactions, graphics, sound, and multiplayer functionality.

  • Social Media: The strategy may encompass testing user registration, profile management, content sharing, privacy settings, and notifications.

These are just a few examples, but the functional testing strategy can be tailored to meet the specific needs of any business domain. It's important to align the testing activities with the unique functionalities and requirements of the system being developed.


Functional testing tools and services 

There are some great tools and services out there to help you improve your functional testing.

Global App Testing 

Global App Testing is a service which allows you to launch manual tests anywhere in the world and receive your test results back in less than two days. 

Crowdtesting, a method of product testing, involves utilizing a diverse group of professional testers worldwide. Global App Testing, for instance, currently boasts a pool of over 90,000 testers (as of July 2023) and expects continuous expansion.

Crowdtesting combines the benefits typically associated with specialized testing service providers and automated tests. These advantages include:

  • Extensive availability of devices and manpower: This eliminates the complexities associated with device management, particularly in tasks like version testing. Additionally, it offers a broad range of devices, software versions, and, if needed, testers from different demographics and geographic locations.

  • Global availability and a large tester base: This enables the launch of numerous tests at any given time, with swift turnaround times. This flexibility allows for seamless integration of tests within agile sprints, incorporating overnight or weekend testing. Crowdtests are slower than automated tests but significantly faster than traditional manual testing methods, offering a significant advantage.


Different kinds of functional testing tools 

We integrate with the following tools and services:

  • GitHUb
  • Jira
  • Zephyr 
  • TestRail
  • Azure DebOps
  • Slack

They fit the following categories:


Functional Test Management Tools

Including TestRail, these tools help in organizing and managing test cases, test suites, test plans, and test execution results. They often provide features for test case creation, version control, scheduling, and reporting.


Functional Test Automation Tools

These tools assist in automating the execution of test cases. They enable testers to record and playback user actions, generate test scripts, and execute tests repeatedly. Test automation tools also offer features for data-driven testing, regression testing, and integration with continuous integration/continuous delivery (CI/CD) pipelines.


Test Frameworks

Test frameworks provide a foundation for organizing and executing automated test scripts. They typically include libraries, coding conventions, and guidelines for structuring tests. Frameworks often support various programming languages and offer utilities for assertions, test data management, and test reporting.


Web Testing Tools

These tools specialize in testing web applications. They provide capabilities for simulating user interactions, validating web page elements, handling dynamic content, and performing cross-browser testing. Web testing tools may also offer features for load testing and performance testing.


Mobile Functional Testing Tools

Specifically designed for mobile applications, these tools assist in testing mobile devices and emulators. They enable testers to verify functionality, user interface, device-specific behaviors, and performance of mobile apps. Mobile testing tools often support both Android and iOS platforms.


API Testing Tools

API testing tools focus on testing the functionality and performance of application programming interfaces (APIs). They facilitate sending requests, validating responses, handling authentication, and verifying data exchange between systems. API testing tools may support various protocols such as REST, SOAP, and GraphQL.

Performance Testing Tools

These tools help in assessing the performance and scalability of applications under different loads and conditions. They measure response times, throughput, resource utilization, and identify performance bottlenecks. Performance testing tools often include features for load testing, stress testing, and capacity planning.


Security Testing Tools

Security testing tools aim to identify vulnerabilities and weaknesses in applications. They assist in detecting common security flaws, such as SQL injection, cross-site scripting (XSS), and insecure authentication. Security testing tools may include vulnerability scanners, penetration testing tools, and code analysis tools.


Code Review Tools

These tools focus on analyzing the source code of applications to identify programming errors, coding standards violations, and potential bugs. They help in improving code quality, maintainability, and adherence to best practices. Code review tools often support static code analysis, code metrics, and code review workflows.


Get started on your QA strategy with functional testing

If you’re interested in crowdtesting with Global App Testing, you can do so below.


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