GuidesProduct developmentWhat is integration testing?

What is integration testing?

Last updated

11 March 2024


Dovetail Editorial Team

Reviewed by

Mary Mikhail

Every software system comprises many individual parts, often known as modules. Even if they work well individually, they must also work well together. Integration testing can help with this. It’s a type of software testing used in product development that involves gradually integrating software modules before testing them as a unified group.

Incorporating integration testing into your software project makes it more solid overall, making your customers happy and preventing technical issues from occurring later on.

Read on to find out about integration testing and the key steps involved.

Integration testing defined

Integration testing is a type of software testing where modules are integrated gradually before being tested as a group. It usually involves a group of programmers working on different modules to expose any defects in how the components interact.

Integration testing offers many benefits. It can help you identify defects that might not be visible at the unit level, enabling you to fix them before they are integrated. Integration testing can also facilitate collaboration between the team members involved in the project. It helps establish a common understanding and expectation of the software as developers work together to ensure a seamless user experience.

What does integration testing involve?

At its most basic level, integration testing involves integrating a software application’s separate components and then testing how they behave when combined.

Developers use several tools to help them get a better understanding of a product’s strengths, weaknesses, and areas of opportunity. They can also use test driver tools—dummy programs that act as substitutes for end users.

Integration testing vs. unit testing

Integration testing and unit testing are both important parts of the software development process.

Unit testing is conducted before integration testing. During this phase, every piece of code is tested based on its isolated functionality. This process reveals granular insights that can be beneficial to developers and project managers. Integration testing then focuses on across-module functionality.

The primary difference between the two methods is that unit testing focuses on individual modules, while integration testing looks at the whole.

Manual integration testing vs. automated testing

Many developers have strong feelings about whether manual integration testing is superior to automated integration testing. Both approaches have pros and cons.

Manual integration testing allows developers to get closer to the data and potentially understand the levels of performance on a more granular level than automation can reveal. However, manual integration testing can also take much longer.

Automated integration testing eliminates the risk of human error that can sometimes happen with a manual approach. It can also be useful in identifying errors early on in the development process.

The automated approach can be beneficial if your team needs to run certain test cases repeatedly. Having a team member do this manually is time-consuming and potentially a waste of resources. Automation frees up your developers to work on other aspects of the project, including beta testing and tracking.

Integration testing vs. system testing

Both integration testing and system testing are important in software development. Integrated testing runs unit tests on one or more integrated modules to ensure everything works as expected. System testing, on the other hand, tests the entire system, including all modules. 

Why integration testing is essential

Producing reliable software is a journey that can be full of challenges. Performing integration testing enables you to release a more reliable product, as it helps you identify and fix defects that may not be visible at the unit level. It can also reveal flaws in the software design or logic, such as data loss or interface mismatch.

With integration testing, you can become more confident in your product and build trust in your software even as you actively work to reduce the risk of post-launch issues.

Ultimately, the approach helps you build a stronger business from the inside out, boosting the development team’s confidence and ensuring happier customers.

Are there any drawbacks to integration testing?

While integration testing can provide many benefits, there are also some distinct disadvantages to be aware of.

The process can be expensive, especially compared to unit testing. It requires a lot of time and resources and can impact your team’s workload—so it may not be feasible for your team. Integration testing can also present challenges with problem isolation. If multiple parts of a system are involved in an issue, finding the root cause can be challenging and time-consuming.

What are the key steps in integration testing?

Integration testing may vary slightly between organizations. However, every project should involve some basic steps, including the following:

  • Preparing a test integration plan and the required frameworks

  • Deciding what type of integration testing approach you’ll use

  • Involving your team in designing test cases and scenarios

  • Deploying the chosen components to run integration testing

  • Tracking and recording results until you get bug-free outcomes

Follow these key steps repeatedly until the entire system is tested, functional, and completely bug-free. It’s okay if this process takes time, especially if you’re launching a brand-new type of software.

Types of integration testing

There are three main types of integration testing, and each offers unique benefits.

The best choice for your product depends on its complexity, maturity, and position within the portfolio.

1. Big bang integration testing

Big bang integration testing is an approach that involves the integration and testing of all modules at once. This means it’s ideal for small systems with fewer modules.

2. Incremental integration testing

Incremental integration testing is where two or more modules with similar logic and functionality are grouped and tested first. Then, other groups of modules with similar logic are tested until every module or component has been integrated and tested.

This approach is more strategic and methodical than big bang testing, making it more suitable for large teams or organizations with substantial resources.

3. Hybrid approach (sandwich approach)

In integration testing, developers opt to work with a bottom-up or top-down approach. Bottom-up means testers begin with modules at the lowest level, gradually working their way up. Top-down is the reverse of this.

A hybrid approach to integration testing, also known as the sandwich approach, is when developers use both bottom-up and top-down testing simultaneously. This allows for greater flexibility, empowering teams to adjust their testing activities based on unique project requirements.

The hybrid approach also enables you to verify both high- and low-level components at the same time.

Best practices for integration testing

Effective integration testing can take time and effort. By following these best practices, you and your team will produce software that works well every time.

  • Collaboration: always keep the spirit of collaboration in mind during your integration testing. When done right, it requires collaboration not only between members of the same team but from different departments.

  • Tracking:  keep notes along the way and log your testing results so that you can refer to them later. You should also check everything before submitting a project. This will assure you that every bug and issue was properly addressed and fixed.

  • Comprehensiveness: integration testing should be as comprehensive as possible. Test all possible combinations and scenarios to ensure they can work together properly.

Integration testing examples

Integration testing can be effective across industries. It can help you serve customers better and enable more precise team alignment, no matter the business you work in.

An example of integration testing for an ecommerce platform might involve your development team assessing whether customers can shop online without issues.

In this case, you would make sure that each module fits together to allow customers to complete a transaction. Customers should also be able to log in to their online accounts, search for items using your website’s search functionality, select quantities or sizes, and complete the checkout process seamlessly.

In this case, integration testing would involve testing all of these components and having members of your development team complete the checkout process with all variables in mind.

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