In this era of digital transformation, applications hardly operate stand-alone. As your business starts transforming digitally, you need to start connecting on-premises applications, cloud applications, and services to automate end-to-end processes – procure to pay, inquiry to order, and hire to retire. This process is known as application integration. Here, the question comes, how can you identify that different applications are acting seamlessly, transferring data properly, and are aligned with your business objectives. This is where system integration testing (SIT) comes in.

What is System Integration Testing (SIT)?

It is a software testing technique that validates the full functionality when different applications/ systems are working together or integrated with each other. SIT testing involves validation of software, systems, or networks for performance, integrity, and compatibility as a single unit. SIT is performed to test the interactions among several integrated components.

Why do you need to perform SIT?

• Integration often involves disparate applications that are developed by different vendors to operate stand-alone. When these applications are integrated to enhance critical business processes, SIT is performed to validate whether the integrated units function properly as one unit and align with stated requirements.

• SIT is used to address different issues such as inadequate exception handling, API response generation, data formatting, erroneous external hardware interfaces, incorrect third-party service interfaces and error trapping.

Types of System Integration Testing

Incremental Testing:

In this type of SIT testing two or more modules are combined logically and tested. Here, testers can easily find defects at an early stage of development by following step-by-step examination of integrated applications. Incremental testing can be further classified as

Bottom-Up Testing:

In this testing type, the lowest level module in the architecture is tested first. The testing control flow moves from the bottom to the top. The main advantage of this approach is that the minimal identification & troubleshooting time is required.

Top-Down Testing:

In this approach, the top module in the architecture is tested first. The testing control flows move from the bottom to the top.

Sandwich Testing:

This type of testing is also known as hybrid integration testing. The testing approach here combines both top down and bottom-up types. This means that testing is done in both directions – towards higher-level modules (upwards) and towards lower-level modules (downwards) – as the integration process begins at the middle layer (downwards).

Big Bang Testing:

Also known as non-incremental testing type, Big Bang testing is executed when all the modules are assembled into a complete system. All the modules after integration are tested together as one unit.
System Integration Testing Best Practices

Robust test strategy: A robust test strategy should clearly outline the scope, objectives, approach, and schedule for SIT. You need to include different stakeholders in SIT – test managers, integration testers, system architects, developers, and business analysts.

Bring in replica of production instance: To avoid discrepancies and inaccuracies, you should mimic the production environment.

Bring in automation: Whenever you integrate a new system or whenever different integrated systems receive updates, you need to perform regression testing. Since manual regression testing is not only time-consuming but also inefficient, you should bring in test automation to save time, effort, and improve coverage.

Documentation and traceability: If a system is complex, it can be challenging to document and trace system requirements, design, implementation, integration, and testing results. You need a platform that not only automates integration tests but also offers traceability to foster collaboration among different stakeholders.

Conclusion

System integration testing is vital to ensure that different applications are functioning and interacting as expected. SIT also ensures that the right set of data is transferring from one application to another and is received by the suitable stakeholder. However, to speed up the process and to ensure that business continuity remains intact, you need to support it with test automation. Not only does this save your time but also ensures that your integrated applications are robust and risk-free.