Integration Testing vs Functional Testing: Key Differences

Today’s sophisticated business applications require comprehensive testing across various levels for flawless functioning and user-friendly experience. This entails a tactical merging of integration testing and functional testing all through the development cycle. Both these testing categories perform significant yet different functions in application QA.

An understanding of the major differences between integration and functional testing is paramount for test leaders to construct efficient roadmaps. Let’s explore what makes the two approaches different in various aspects of mobile app testing.

What is Integration Testing?

The process of testing the individual application modules which are combined and tested as a group is known as integration testing. Its goal is to verify the interactions between integrated components and find interface flaws. The automated integration testing tools encompass the validation of interfaces between modules and checks that the flow of data is done adequately. It focuses on testing aspects like:

  • APIs and service calls between app layers
  • Database operations and data exchange
  • UI navigation across various parts
  • Authentication and single sign-on
  • Integration with external systems

Some of the well-known integration testing techniques include incremental and hybrid methods. Automated API testing plays a crucial role in running the integration test scenarios.

The process entails modeling of use cases, payloads and test data for integration points checking. As a result, the testers validate smooth integration between frontend logic, database and other layers. Stressful scenarios, like unreliable networks, interrupted connectivity and peak loads are simulated.

When conducted properly in iterations, integration testing detects interface mismatching, incompatible data structures and inconsistent data flow as well as other integration defects at an early stage. This facilitates troubleshooting and minimizes project risks because it prevents late-stage failures.

Things to Know About Functional Testing in App Development

Functional testing is a vital testing process that checks whether the application works as expected in line with the specified requirements. It aims at verifying the end-to-end business workflows and use cases from an end-user point of view.

Functional testing for web-based applications involves flows such as user registration, login, profile management, core site navigation payments and search validations along with integration into external systems. Testers play the role of end-users and ensure that all defined requirements are met.

Functional testing of mobile apps comes down to common user journeys, gestures, interrupts, data validation and UI elements as well as device-specific features and compatible behavior on different OS versions. Exploratory testing uncovers edge cases.

In the case of enterprise applications such as ERP and CRM, functional testing verifies complicated workflows, field calculations, reports, exports and role-based access across modules. Real-world stability is achieved through big data and performance testing.

The used range includes black box testing of the UI layer, business logic, calculations, integrations, error handling security and database operations. Manual validation is aided by automated scripts, unit testing, and UI object testing.

The purpose of functional mobile app testing is to make apps deliver the correct features with high code coverage as possible. Defects caught include crashes, calculation errors, data loss, workflows stuck and invalid handling of valid/invalid input. 

Major Differences Between Functional and Integration Testing in App Development


Integration testing seeks to ensure seamless integration between the different modules and interfaces that constitute an application environment. It aims to confirm the interfaces and data flow between components.

On the contrary, functional testing is aimed at ensuring that an application satisfies all business and technical specifications provided by stakeholders. This goal is to make sure that the application produces the desired functions and processes.


Given that integration testing focuses on communications between modules, its reach encompasses all the various interfaces and touchpoints. These include API calls, database interactions, login hand-offs, UI navigation and other interfaces.

The scope of functional testing is end-to-end, designed to mimic real use cases and workflows. It includes performing all critical activities, user journeys, screen flows, business rules, calculations and connections in an integrated setting.


Integration testing is usually performed in earlier stages of the development life cycle by developers to test connections between application units developed by them. Different integration techniques such as big bang, incremental and sandwich are used based on the system architecture.

Finally, functional testing is performed by QA testers to test the finished application against requirements. It includes comprehensive black box testing of each functional element and their orchestration as user workflows.


Automated integration testing tools concern interactions between known interfaces, making automation more feasible. API automation is prevalent in rigorous integration testing.

The functional flows are more difficult to automate and demand human sense. Although automation supports functional testing, manual validation cannot be done away with particularly in matters of UX. The use of intelligent test automation is widespread.


In integration testing, heterogeneous technologies and complex distributed data transactions present difficult problems. These include covering exponentially large workflow combinations, testing integrated 3rd party services and handling multi-device environments for functional testing.

Web Application Testing

Integration testing for web apps deals with aspects such as frontend and back-end connectivity, database actions, API flows, and organized single sign-in to make sure that website elements work together properly.

Functional testing for web apps includes user registration, profile management, navigation between the pages, field validation and payment integration. Testing all functional elements.

Mobile Application Testing

Integration testing for mobile apps ensures proper integration between app modules, native-hybrid interactions, connection with back-end services, data exchange and API tests.

Mobile app functional testing includes various real-life workflows, UI validations, gestures, field rules and device-specific features like calls/text interruption, among others.

Integration testing ensures that the interfaces between various modules in an application are functioning normally. Its focus is on the interface points to identify plumbing defects early. Functional testing verifies that the system meets its functionality, as required by the business. 

Modern applications are validated by integration and functional testing that complement each other. The process of integration testing guarantees that the components must be connected correctly, while functional testing ensures functionality in a real-life setting. The optimal utilization of both testing approaches during the development process leads to efficient enterprise applications that surmount customer satisfaction.

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