Complete Guide to Functional Testing and Its Types

September 07, 2018 

Complete Guide to Functional Testing and Its Types

What is Functional Testing and Types of Functional Testing?

Software testing executes a program or application to check whether the actual results match the expected results and to assure that the software system is Bug- free. It can be either done manually or using automated tools. Software testing classified into two categories -

  • Functional Testing
  • Non - Functional Testing

Functional Testing reviews every aspect of a piece of software to make sure that it works correctly. Functional testing verifies that system should perform as expected when its features exercised by some other system or directly by a user.

Common Functional tests -

  • Unit Testing - Unit testing should start at the very beginning to assure that each block of code/unit performs its intended manipulation of inputs into desired outputs for the next module. Tests an individual unit/component of software to validate that each unit of the software performs as designed.
  • Integration Testing - Takes multiple individual units/component of the software and tests them as a group to ensure that the unit modules connect as expected and convey data and commands throughout the system per the specifications built.
  • Smoke Testing - Smoke tests are a subset of test cases which tests the major/critical functionalities of software in a non- comprehensive manner to ensure the software works well enough to move on to additional tests. Execute before any detailed functional test or regression tests performed on the software build.
  • Sanity Testing - After receiving a software build verify that minor changes and fixes applied to the code body do not have unexpected side effects in, apparently, separate parts of the system and to confirm that the bugs have fixed. If sanity tests fail, the build will be rejected to save the time and costs involved in more rigorous testing.
  • Regression Testing - Verify that the later feature additions and bug fixes(due to which code changes)not adversely affect existing features. Regression Testing is nothing but the full or partial selection of already executed test cases which are re-executed to ensure existing functionalities work fine.
  • User Acceptance Testing - This the last step before software goes live, user acceptance tests make sure it can handle required tasks in Real- World scenarios, according to specifications. End users typically perform these tests during the Beta testing period.

Benefits of Functional Testing

Functional Testing has the following Benefits -

  • It ensures that the customer or end- user is satisfied.
  • It produces a defect-free product/software.
  • It ensures the all the requirements should be met.
  • It ensures the proper working of all the functionalities of an application/software/product.
  • It ensures that the software/product works as expected.
  • It ensures security and safety.
  • It improves the quality of the product.
  • The risks and loss associated with the product/software reduced.

How Functional Testing Works?

When conducting functional tests, you should typically need to follow a process that looks something like this -

  • Use test data to identify the inputs.
  • Determine the expected outcome based on those inputs.
  • Run test cases with the proper inputs.
  • Compare actual results with expected results.

Following this method, if the actual results and the expected results will match, then conclude that the software functions correctly and that the test has passed. If they do not match, then there is an issue with the software.

Two Perspectives -

Requirements- focused testing, prioritizing requirements based on risk criteria to evaluate the most critical and essential features and functions first.

Business - process focused testing, which relies on the knowledge of end-user business requirements to evaluate application performance in the context of use cases.


Why Functional Testing Matters?

It can be simple to dismiss software testing as an unwanted investment of time and money. But for so many organizations, one small bug spiraled out of control. Embarrassing software glitches in the product might make a brand go viral but in a wrong way. No requirement of the significance of proper software testing techniques the hard way.

Examples

Apple's recent iOS 11.1 updates came with a host of glitches. Users report that the new system did not type the letter "I," and emitted a cracking sound during phone calls, so they didn't buy iPhone 8.

Apple was not the only company to fail to deliver on a cell phone’s most basic function this year. One of its competitors, the Android OnePlus 5, disconnects when users try to call 911.

Removal of unsavory content from the news feed. Identity revelation on Facebook of the hater's group.

Timing anomaly in GPS causing a global GPS time delay of a whopping 13 microseconds, affecting users for several hours.

Delay in testing caused the release of BART's new fleet of train cars pushed back by several months indicating exterior of the new trams is good to go, but that performance monitoring may be holding up the process.


 

How to Adopt Functional Testing?

  • Black Box Testing
  • White Box Testing
  • Gray Box Testing

Black Box Testing

Black Box is a testing technique in which the functionality of the software tested without looking at the internal design/code/structure/implementation details and knowledge of internal paths of the software. It examines the functionality of an application based on the specifications.

White Box Testing

White box tests predicated on knowing precisely about code/structure/implementation under test and tests executed to verify the robustness of the code than its absolute functionality. It is performed at the beginning of the development process with unit tests and in the early parts of the integration phase. Black box testing is typical of the latter stages where a response to specific operating scenarios is essential.

Gray Box Testing

The third type of testing is a combination of a White and Black box. Gray Box Testing happens as development moves into a crossover zone towards the end of integration and the beginning of usability. A gray box is a device, program or system whose workings are partially understood.


Best Practices for Functional Testing

Any functionality is tested by providing inputs, observing its output and comparing the actual results with the familiar ones. Here are some effective procedures or best practices that may come handy while you perform functional testing -

  • Reusable test cases - Develop test cases may take time, so the more reusable you can prepare test cases, the better. While writing reusable test cases, write in a simple language that is easy to understand, and the test steps short and easy to execute. Then, help to reuse test cases when appropriate rather than reinventing the wheel each time, be sure to stay organized by managing those test cases in a single source of truth like a test case management tool.
  • Test data and configurations drive design tests - Relying on test data and configurations to develop test steps will make sure you have everything that you need to complete the tests and fully understand the results. For example, have right login credentials to have access to all of the functionality to test and ensure correct input data because it will impact whether a test will pass or fail. Ultimately, pay close attention to test the data and configurations at each step of the way, as these details are much important when informing developers, product owners about issues and understand the causes of those issues.
  • Prioritize high risk and complex test cases - When it comes to manual testing, prioritize complex risk and high test cases, as these are the ones that most need a human at the steering wheel.
  • Consider opportunities for automation (without going overboard) - Although don't automate all of the testings, look for opportunities to embrace automation to save the time and make it easier to run specific tests more often. Remember to take an automated first approach when considering which tests are best to execute manually and which tests are more suitable for automation. Keep the complexity on top of mind.
  • Don’t overlook the importance of documentation - Documentation is a critical piece of manual testing, especially when it comes to tracking the issues through reports. A good report is essential to help others on the team (testers and developers alike) understand what problems exist and how to find these issues. To make a strong report, an ordered list of steps to recreate the problems that are much easy to understand and follow, details on the basis severity and priority of the issue, and insight on what should happen if the issue resolved.

Best Tools for Functional Testing

In the era of automating everywhere, applications are developed specifically for the work done quickly and efficiently. Highly dependent on minimizing work efforts with the help of various tools.

There are varieties of tools available for testing. Just type "test tool, and find a wide range of answers, from open source to best of the breed—based on many different assumptions. Out of that much testing tool, some listed below.