Functional Testing vs Integration Testing: Which One to Use, and When?

Functional Testing vs Integration Testing: Which One to Use, and When?

Trouble Logging in Delays Software Launch?

Imagine a situation where software that was supposed to be launched encountered a problem when people tried to log in. It turned out that the login information provided needed to be corrected, and no one could access the software.

This unexpected issue caused a delay in the software's launch because it was crucial for users to be able to log in successfully. As a result, the development team had to work hard to fix the problem and ensure users could log in without issues before releasing the software to the public.

This is one of the common scenarios in the world of software development world. As a result, many software launches have been delayed for months or years because of last-minute errors.

The question arises, “Why weren’t these errors caught during development?” The answer lies in software testing processes.

Consortium for Information and Software Quality states that US companies lost $2.08 trillion due to poor software quality.

Fortunately, businesses can avoid these mistakes entirely with the proper testing method. Here, we will discuss two such ways, called integration and functional testing.

Let’s begin.

What is Functional Testing?

Functional testing answers the question, “Does it work?”

Suppose you have a microwave. You want to ensure that the food is heated and that all other functionalities work as they should. That's what functional testing is all about!

To ensure they work correctly, we try all the different functions and features, like baking, heating, grilling, temperature setting, and more. This helps ensure the program is functional and does what we expect.

Standard tools used for functional testing are HP Unified Functional Testing (UFT), JUnit, Appium, Selenium, TestComplete, etc.

Here are a few examples of functional testing for a banking app.

  • One functional test can check whether users get error messages when they enter the wrong pin.
  • Another functional test could be to check what happens if users forget their password. Can they reset it and log in to the interface again?

When to Choose Functional Testing?

  • If you have introduced a new feature or module, it's necessary to do functional testing.
  • If you have upgraded software recently, functional testing is essential to ensure that no feature is broken due to the upgrade.
  • In the case of software migration too, functional testing is essential to ensure that apps are functioning as expected on the new platform.

Pros & Cons of Functional Testing?

Pros of Functional Testing:

  • Confirms whether the software meets clients' requirements: Every software project has specification documents that must be followed. Functional testing validates these requirements by checking whether each function works as intended.
  • Heightened user experience: Functional testing is conducted from the user's point of view, which means it will test all the software features and ensure they are user-friendly.
  • Better security: Since every software function goes through checks, bugs, and errors are caught early. Thus, reducing the chances of software failure.

Cons of Functional Testing:

  • It is detailed testing, so the process is slow. So, testing new features takes a long time if you introduce them back to back.
  • At times, it can be less accurate as it just checks the actual function of the software and misses the logic part. Thus, making it challenging to find the bugs under normal conditions.
  • It's more expensive because of the complex tools involved.

What is Integration Testing?

Integration testing is a type of software testing that is done when all the software components are tested together.

Imagine you're building a LEGO house. First, you create the walls and windows separately and then try to fit them together. If they don't work, you make changes until they do. So, like with LEGO, you can apply the step-by-step approach and testing to software development.

The software has different modules; integration testing helps us check the errors when these modules are pasted together. Here is where you can check that the various modules are communicating with each other, that data is flowing correctly between them, and that the entire system is behaving as expected. You can avoid costly mistakes by testing individual parts and ensuring they fit together seamlessly.

Some top integration testing tools are Rational integration tester by IBM, Citrus Integration Testing, Jasmine, LDRA tool suite, and Tessy by Razorcat Development GmbH.


Suppose you are testing integration links on an e-commerce website.

So, when verifying integration links between login and the home page, you can check whether the user is getting redirected to the home page by entering the correct credentials. If it does, then the test is considered passed.

When to Choose Integration Testing?

Choose, Integration testing when:

  • You have third-party integrations: If your software integrates with third-party components or services, integration testing is necessary to ensure that the integration works as expected and doesn't negatively impact the rest of the application.

Pros & Cons of Integration Testing

Pros of Integration Testing

  • Improves system reliability: Integration testing helps ensure that different system components work together as expected, improving the software's reliability.
  • Provides more excellent testing coverage: It tests the entire software as one entity, which improves testing coverage.
  • Helps catch bugs early: Identifies issues before they become too big to handle. This can save time and money and prevent potential problems from reaching the end users.

Cons of Integration Testing

  • Integration testing requires the creation of stubs and drivers, which can increase the testing time. Moreover, if not done correctly, it results in inaccurate output.
  • If legacy and new software are integrated, testing becomes complex.

What is the difference between functional testing and integration testing?

Functional testing ensures that software works as expected while Integration testing is a subset of functional testing that checks the interactions between two software modules. Integration testing always happens after unit testing.

Also Read - Test Cases in Software Testing


Preventing Software Errors Is Better Than Fixing Them

In conclusion, testing is crucial in software development as it helps detect errors before they impact users. However, as seen from the statistics, only four users out of 100 usually complain to the company when errors surface; the rest 96 leave without giving feedback resulting in lost business and a negative reputation. Therefore, it's important to prioritize testing and invest in professional software developers who follow best practices to ensure flawless results.

That said, prevention is better than cure. It's always good to have minimal errors rather than spending all time fixing them. Hire developers from Clarion Technologies are mindful of the best software development practices such that the result is flawless. By working with a team of experienced developers who prioritize testing and follow best practices, you can rest assured that your software will be of the highest quality. To ensure maximum customer satisfaction, get in touch with us today.


Author Bio: Binny is a seasoned content marketer in the tech field. With a strong passion for storytelling, she understands digital marketing through creative content strategies. She deeply understands the customer journey and knows how to craft thoughtful content that inspires action. Binny continues to thrive in her role, using her skills to help demystify complex tech concepts for a broader audience.

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