Integration Testing and Its Importance in Software Development

Incompatibility is a common issue in software development and can happen for many reasons, such as different versions, data format inconsistency, or contrasting process logic. Integration testing is the process that helps find these inconsistencies between different software modules. Integration testing is done prior to system testing and after unit testing which helps in finding defects in the activity between units that are integrated using test drivers and test stubs. It is a part of software testing that examines data communication between software modules. 
In this article, we will explain what integration testing is and the significance of this testing approach in software development.
What is integration testing? 
Integration testing is used to find data loss or miscommunication issues between different software modules, which helps ensure that the integrated modules work smoothly and enhance the reliability and efficiency of the software. Integration testing is also referred to as I&T (Integration and testing), which is string testing or thread testing. The purpose and the goal behind integration testing is to identify and resolve issues related to integration at an early stage of the development cycle.
The process integrates software modules and tests them as a group, which helps in confirming that the total system or a sub-system works well when integrated or exposes the errors between different codes.

Integration testing can be done in two ways: the Big Bang approach and the Incremental approach. 
In the Big Bang approach to integration testing, all the modules or components are integrated and then tested as a single unit. This method of testing is used when the software development and delivery has a limited time schedule, and the development teams are working on multiple parts of the software simultaneously. The advantage of this approach is that all components are tested at the same time. The disadvantage is that it is difficult to spot individual component errors. The approach is effective for small systems. 
In the incremental approach to integration testing, individual modules are combined and tested one by one, until all the modules are logically added to make the application. This method of testing can identify errors in the modules at an early stage, where the focus is to check the interface, the flow of information and the links between different modules. 
Benefits of integration testing
Seamless integration
Integration testing helps ensure that each software module works together to form a unified software system. When different modules are integrated this testing process detects inconsistencies and discrepancies which can then be addressed. The end result is that the software works smoothly to increase the overall performance of the software. Integration testing also enables error detection at an early stage of development which makes debugging easier and faster. 
Inconsistency in code logic
Development of individual software modules can raise the risk of discrepancies, which can then lead to errors or unexpected working when these modules or components are integrated to make a complete system. Integration testing can be used to find inconsistencies in code logic which can be corrected at an early stage of development. 
Addresses changing system requirements 
As the software requirements changes and evolves, it may be necessary to add further modules, modify existing ones or remove some modules to meet these changing requirements. These changes can cause the existing system to get disrupted, leading to errors or even system failure. Integration testing ensures that the changes do not affect the system and it works just as correctly and efficiently as before. 
Reduces error-fixing costs
Integration testing can find errors in various modules during the development cycle. These errors can be rectified during the early stages of development when the system is less complex, reducing the costs associated with fixing these errors. Integration testing not only ensures that the software functions smoothly but also helps with cost efficiency by reducing the expenses associated with rectifying errors. 
Design improvement 
By finding errors and defects during the testing phase, integration testing can help in design improvement. Errors or flaws in the software module can be indicative of a design flaw that can be corrected, leading to improved design. 
Exception handling
Exception handling ensures that the software system handles any unexpected input or event without generating errors or even failing. When complex software systems are designed, their modules are usually developed independently and may not handle exceptions consistently. Integration testing can identify and enable early and faster rectification of such irregularities. Modules can be tested for different scenarios that may trigger such exceptional behavior, and rectified to handle such inconsistencies properly. 

Conclusion 
Integration testing is essential to ensure that the quality of the software is not compromised. It ensures that each module of a software system functions properly when integrated to make the whole system. Since it can identify and rectify errors at the early stages of development, it helps reduce the cost of fixing errors and ensures that the integration is seamless. It can be used to handle changes in system requirements, spot inconsistencies in code, and be used for exception handling. Integration testing can help build robust, efficient software and is an essential part of quality assurance services.