After recently reading up on unit testing and having some exposure to it in class, I figured the next step would be to look at integration testing. With plenty of blogs to choose from, all giving pretty similar information on integration testing, I chose to highlight the blog published by Katalon (https://katalon.com/resources-center/blog/integration-testing). This blog provides more information into certain aspects of Integration testing, such as explaining some differences between low- and high-level modules. This extra insight helps piece together a lot of the questions I had while reading other blogs on the topic.
What is Integration Testing?
Integration testing is a software testing method that involves combining individual units together and testing how they interact. The main purpose of integration testing is to ensure that each module works together as intended and does not create any unforeseen bugs. Each module should be individually unit tested before integration testing.
Why is Integration Testing Useful?
Integration testing helps identify bugs that may not be seen in unit testing. These bugs can come from a multitude of places. Inconsistent logic between different programmers, modifying code, data being transferred incorrectly, poor exception handling, and incompatible versions may all lead to bugs that only appear during integration testing. Integration testing helps identify these bugs, and depending on what model is being implemented, may easily help find the locality of the bug.
What are the Primary Approaches to Integration Testing?
There are two main approaches to performing integration testing: the big bang approach, and the incremental approach. The big bang approach involves integrating and testing all modules at once. This is great for small systems that do not have much complexity however, this means finding the location of a bug will be harder with a complex system. When systems become larger and more complex it may be best to switch to incremental testing. This is an integration testing method where modules are combined and tested in smaller groups. These groups continue to combine with other groups until the system is tested. Three common incremental integration testing methods are the bottom-up approach, top-down approach, and a hybrid approach. Bottom-up starts by integrating the lowest level modules together before adding higher level modules. Top-down does the opposite where it starts by integrating the highest-level modules before adding the lower ones in as tests pass. The hybrid, also known as the sandwich approach, is a combination that may alternate between testing the top level and bottom level components.
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