Functional vs Manual Testing: What You’re Missing

I often witness confusion about the difference between functional testing and manual testing. Both of these terms play a significant role in quality assurance. This blog post intends to clarify the difference between functional testing and manual testing and dive into these terms’ meanings.

Is functional testing and manual testing the same?
No, functional testing and manual testing are not the same.
Functional testing is the type of testing that helps testers validate an application against the functional requirements. There are two ways to execute functional tests:

  • Manual testing (done by humans)
  • Automation testing (done by machines)

Manual testing and automation testing are methods used to execute functional tests.

Now that we have covered the fundamental differences in functional and manual testing, let’s dive deeper into what each term means and include some examples.

Manual testing is a testing method under functional or non-functional testing. As I have mentioned, functional testing and manual testing are not the same. In manual testing, we test the software manually, i.e., without the help of any automation tools.

In functional testing, we can test the software’s functionality in several ways, i.e., unit testing, integration testing, end to end testing, regression testing, and more (detailed later in this post). In non-functional testing, we generally do performance testing, security testing, usability testing, and compatibility testing. We can test manually or with the help of automation tools.

What is Functional Testing?

Functional testing is a type of testing that helps the testers validate the software system against the functional requirements or specifications.

In functional testing, we test each of the software’s functionality, such as checking all the web page links, form inputs, checking that a given input produces an expected output, and verifying results against the requirements.

Functional testing verifies user interface, APIs, database, security, Client/Server communication, and other application functionality under test. The testing can be done either manually or using automation tools.

In functional testing, the prime objective is to ensure the application’s functionalities are working as expected.

Functional testing mainly concentrates on the following aspects:

  • Functional: Testing the main functions of an application are working as expected.
  • Usability: Testing whether a user can freely navigate through the application without any difficulties.
  • Accessibility: Testing the user accessibility options of the application.
  • Error Handling: Testing error conditions and whether suitable error messages are displayed.

The following is a list of some popular tools to aid in automating functional tests

  • Selenium – A popular open-source functional testing tool
  • QTP – Very user-friendly Functional Test tool by HP
  • Used mainly for Java applications in Unit and System Testing
  • SoapUI – This is an open-source functional testing tool, mainly used for Web service testing. It supports multiple protocols such as HTTP, SOAP, and JDBC.
  • Watir – This is a functional testing tool for web applications. It supports tests executed on the web browser and uses the ruby scripting language.

The following is a list of functional testing processes

  • Unit Testing
  • Smoke Testing
  • Sanity Testing
  • Integration Testing
  • White-box testing
  • Black Box testing
  • User Acceptance testing
  • Regression Testing

What is Manual Testing?

Manual testing refers to testing done manually by humans while searching for bugs or anomalies in an application. Testers follow a written test plan that describes the set of scenarios and steps to execute tests and verify the expected results.

Functional testing also considers the performance of the application from an end user’s perspective. We need to verify the application’s actual behavior against expected behavior, and any difference reported as a bug.

In manual testing, we have to test the application with an end-user mindset. We have to think about the customer perspective and note down all the issues, UI/UX flaws, design improvements, and how we can provide a better experience to the end-user.

Manual testing plays a significant role in software testing. Every project needs some form of manual testing before automation.

Here is a list of the main steps for performing manual tests

  • Read and understand the functional requirements
  • Identify and prepare test inputs (test data)
  • Identify the expected outcomes for your test inputs
  • Write a test plan with test cases to cover the functional requirements
  • Review the test cases with your team
  • Execute the test cases comparing actual and expected results
  • Report bugs and improvements
  • Verify the failed tests again once the bugs are fixed.

Functional Testing Example: User Sign-up

Let’s use a sign-up journey as an example.

Consider the development team has delivered a sign-up page for testing on a website.

The web page has a simple form to fill in a user name field, a new password field, and a field to confirm your new password.

The expected behavior is that the sign-up submission is successful when

  • the user name doesn’t already exist
  • the two password fields match

If the tester can submit the form successfully without matching passwords, then the test case has failed, and a bug is reported to the development team.

The sign-up form is a typical scenario of a functional test that can be automated. But when working on new functionality, there will always be a need for manual testing before an automated test is ready and stable.

On such vital features, as in signing up new users, manual testing will always play an essential role in testing.

Stages of Functional Testing

Unit Testing

In unit testing, we verify the individual components or units of the code. A unit test is the smallest testable part of any application. It focuses on testing the functionality of individual components within the application. Developers often use unit testing to discover bugs in the early stages of the development cycle.

A unit test case would be as fundamental as clicking a button on a web page and verifying whether it performs the expected action. For example, it ensures that a share button on a webpage lets you share the correct page link.

Integration Testing

In integration testing, we test multiple integrated units as a whole. For example, a shopping cart purchase integrates pricing all the items, a shopping cart total functionality, and payment functionality to execute the transaction.

This approach helps evaluate how several components of an application work together. Performing integration testing parallel with development allows developers to detect bugs early on in the development lifecycle.

System Testing

In system testing, we test all the units and their integration. It involves testing of all the integrated modules of the application as a whole. System testing helps verify whether the system meets the specified requirements in terms of functionality and integration.

System testing includes functional testing, regression testing, performance testing, and user experience testing.

Acceptance Testing

Internal or external stakeholders usually do acceptance testing. The main goal of acceptance testing is to verify whether the product meets the requirements and if any improvements or new requirements are necessary.

Members within the organization perform internal acceptance testing, also known as alpha testing. A limited number of actual end-users perform external testing, also known as beta testing.

Beta testing helps evaluate how well the product satisfies the user’s expectations. It also identifies bugs in the last stage before releasing a product.

Types of Functional Testing

White-Box Testing

White-box testing, also known as glass box or transparent testing, is a testing approach that integrates the application’s internal code or structure in testing.

White-box testing is a method mostly used for unit testing. White-box testing also covers specific techniques like data flow testing, control flow testing, decision coverage, and path testing.

Black-Box Testing

Black-box testing is a testing approach where there is no knowledge about the application’s underlying structure or code. The purpose is to verify that an input to the application produces an expected output, regardless of the underlying technology.

In black-box testing, testers interact with the application just as an end-user would. Black-box testing helps to discover some bugs typically overlooked in earlier testing stages.

Grey-Box Testing

The Grey-Box testing approach is the combination of both white- box and black-box testing techniques. This approach aims to identify any bugs present either due to inappropriate usage or structural flaws.

Wrapping up, functional testing is a set of quality assurance processes for testing an application’s functionality and ensuring it works as defined in the product requirements. Manual testing is a functional testing method done by humans.


My name is John Antunes and I am passionate about helping others succeed in the field of software testing. With over a decade of experience testing a wide variety of software applications and managing QA teams, I have gained valuable insights and expertise that I am excited to share with you. That's why I created - to inspire and empower testers to take their careers to the next level. Whether you're just starting out in the industry or looking to enhance your skills, I am here to guide you every step of the way. Let's work together to achieve your goals and make your dreams a reality.

Recent Posts