The Art of Integration Testing: Let's Get Connected!

by Dmitry Kirsanov 20. November 2023 04:00

By now, we all understand that the term 'integration testing' confidently wears many hats in the software universe. Just like the chameleon changing its colours, integration testing adapts and takes on a sense of variety in different software landscapes. However, when we peek into the court of professional testers, it often refers to testing a software system through the lens of its integration points with external systems. Let me paint you a picture to illustrate this further.

Imagine a robust software system that acts as a modern-day Hermes, retrieving patient vitals and lab test results from external systems. Its crucial task? Alerting clinicians to any emergencies based on the external data it receives. We can put our system through its paces by feeding it faux data, ensuring the business logic of our alert system operates with the precision of a Swiss watch. This hairline focus on our system, either through the UI or directly against the backend logic, serves us well when our primary concern circles testing our own business rules.

However, at some point, we must pivot our focus from our metaphorical belly button and look out into the wide world where our system interacts with real deployed instances of these external systems. The act, my dear readers, is called integration testing. It allows us to confirm that we are interfacing flawlessly with these systems, accepting the data they lavish upon us as expected, without any surprises in the form of unprocessed data or unexpected errors.

Sure, we can conduct integration testing in various ways, each bearing their distinct flavours – automated or manual, meticulously scripted like a Broadway play, or more fluid and exploratory. Similarly, the reasons to invite integration testing to the party can differ. You could have it as a distinguished guest at your regression activity or the prime attraction at your feature confirmation testing.

We need to acknowledge that our software systems aren't introverts. They enjoy the company of other systems, integrating with them, and often these ties are valuable enough to necessitate keen attention and focused testing. The perfect setting for conducting integration testing? An environment that links to real, live instances of the systems we mingle with. Of course, we are usually not speaking about production instances of those external systems, unless our system only reads data from an external brother in arms.

Integration testing shines in situations where our system leans heavily on one or more external systems. Bear in mind though, not all integrations are created equal. The critical dependencies would naturally prompt us to dedicate more time and efforts in their direction.

A sheer reality of the software realm is that our external systems may shift and change without issuing formal invitations. This can cause hiccoughs in production. Cue the entrance of judicious regression and preferably automated integration testing or monitoring, mitigating not only sneaky bugs our team might have introduced, but also fallout from changes in the external system's neighbourhood.

Integration testing demands a live, deployed environment for both our pet project as well as the external dependencies. The closer this environment mimics the production environment, the better it serves our interests. While running isolated tests can help us uncover potential issues, testing in a dynamic, integrated environment can shine a light on those gremlins that might have escaped our notice earlier.

However, our knight in shining armour – integration testing – does meet its own dragons on the battlefield. The task of setting up a suitable environment demands right tools, time, and skill, not unlike preparing for a formal seven-course dinner. This could involve arduously creating an optimal test environment with live connections to external systems, a fixture that can sometimes be about as unstable as a house of cards. The external dependencies may decide to take a nap and your tests grinding to a halt as a result. That's a trade-off you must sometimes make.

The trick to navigate this labyrinth? Remembering your mission. If you're focusing on your application's domain logic, then the integration test approach might not be your leading contender. Give integration testing its rightful place – to diligently test the relationships between systems. After all, like a good relationship, it’s all about communication, understanding, and responding to the changes in our partner's environment.



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