Functional Test vs Integration Test: How are They Different

Functional test vs integration test, how are they different? This article takes you through the definition, advantages, disadvantages, and detailed differences between the two.

Many people have a limited understanding of software testing, and their initial reaction is that software testing is about finding vulnerabilities in applications. This understanding is simplistic.

Simply put, software testing aims to identify potential errors and defects in software with minimal resources, time, and manpower, in order to mitigate the risks posed by software flaws and errors after its release. This is crucial for both businesses and developers.

What is Functional Testing & Integration Testing?

Software testing can be divided into two main categories: functional testing and non-functional testing. Functional testing primarily aims to ensure that the software functions as intended in real-world scenarios for end-users. It includes integration testing and unit testing as its subtypes.

Integration testing, also known as assembly testing, typically builds upon unit testing by sequentially and incrementally testing all program modules. Integration testing examines the interface relationships between program units or components and progressively integrates them to form the desired program parts or the entire system.

Why is Functional Testing Needed?

Functional testing ensures that the system implementation aligns with the requirements from the user's perspective. Since functional testing is based on black-box testing, testers are unaware of the internal implementation of the application. This allows them to uncover issues that developers may not have detected and identify potential omissions. By conducting comprehensive tests on the system's functionality, it verifies whether the system performs operations as expected and provides correct outputs. This helps ensure that the system's functionality meets user expectations and business requirements.

Functional testing also reveals any neglected or overlooked features by developers. Testers execute various test scenarios, covering different inputs and usage situations, to confirm that the system functions correctly under different circumstances. Additionally, functional testing can simulate scenarios such as erratic operations or deviations from established procedures to evaluate the application's fault tolerance and security.

Why is Integration Testing Needed?

Integration testing is important to ensure that modules work together seamlessly, even if they function correctly individually. Some issues may only arise during the integration of modules, which cannot be identified through separate unit testing. Integration testing helps uncover potential problems that may exist at a global level, ensuring that the system achieves the expected functionality as a whole.

Integration testing complements unit testing (UT) and system testing (ST) because they focus on different points. Unit testing focuses on testing the functionality within a module, while system testing verifies the functionality of the entire system. Integration testing, in turn, aims to verify that the interfaces and interactions between modules work properly to ensure that the modules are integrated correctly. Integration testing identifies problems implied by the axiom of anti-decomposability and the axiom of anti-composition and checks the correctness and consistency of the system from a holistic perspective.

Functional test vs integration test, what is the difference? Let's create a simple table to compare the differences between functional testing and integration testing:



Functional Testing

Integration Testing


To verify if the software meets functional requirements from the user's perspective.

To verify the integration and interaction between multiple components or modules.

Testing Level

Primarily at the module or component level.

At the integration level, combining multiple modules or components.


Individual module functionality.

Interactions and interoperability between modules.

Test Techniques

Primarily employs black-box testing techniques.

Utilizes both black-box and white-box testing techniques.

Test Dependencies

Does not require complete system integration.

Requires partial or complete system integration.

Problem Resolution

Addresses functional issues within a module.

Addresses integration-related issues and module interactions.

Test Coverage

Specific functionality of each module.

Overall system behavior and integration points.

Team Involvement

Testing team and quality assurance personnel.

Developers, testers, and system integrators.



Functional test vs integration test, both of them have their own functions and roles and work together to ensure the quality of the final application. If you are looking for the best tool to run functional tests, welcome to WeTest App Functional Testing. We have specifically assigned experienced experts to customize a plan based on the functionality of your app, ensuring the completeness, correctness, and suitability of each feature, guaranteeing the delivery of excellent quality in the end.

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