In matters of API testing, you’ll likely come across two terms: API mocking and API service virtualization. What these two have in common is that their outputs—mocks and virtualizations, respectively—are “test doubles,” or replacements for the API’s actual production objects. They are both relied on during the testing phase to simulate attributes of the API, all without upending the work-in-progress. But this is where the similarities end, as API mocking and API virtualization are two very different testing processes with different end goals.

How API Service Virtualization is Still Better Than API Mocking

The problem arises when one of these is left out of API testing. Oftentimes, it’s API virtualization that gets the short end of the stick. Though API testers can clear a lot of production headway through mocking, they assume it’s the only step they need to complete. What ends up happening is that the team skips virtualization—and consequently, misses the opportunity to do some crucial pre-launch testing.

This article is a treatise for API service virtualization, or a full virtual copy of the API mirroring all its specifications. Here, you can find three reasons why API testers get cold feet about it—and three counter-arguments for why virtualization remains necessary. Keep these in mind when using API mocking within the context of an OpenAPI design and working with a service virtualization, so that both testing phases yield maximum productivity.

Common Reservations Towards API Service Virtualization

The first thing that should be addressed is testers’ hesitance towards API service virtualization. It usually stems from one of the following.

Mocking is Enough

The task of API mocking, or creating imitation software parts that elicit a particular response, is hard enough as it is. It’s an action that requires testers to be attentive, thoughtful, and careful about which API calls to test. Sometimes, the gains achieved by API mocking feel like good enough progress. Thus, once testers get the individual responses they’re looking for, they tend to leave it at that.

Virtualizations are Expensive

Another big reservation the API team may have is the price tag of virtualization. This is a valid concern to have, as full-service virtualizations are admittedly quite costly. The cost of ownership for virtualization can reach tens of thousands of dollars. For small API companies with leaner budgets, this is often something to balk at.

It’s an Unnecessary Extra Step before the API Launch

The last reservation has to do with the number of steps it will take before the API’s release. Time is of the essence in the industry; the longer it takes for the API’s release, the greater the cost on the developing company. Thus, some API teams see the acquisition of a service virtualization as an unnecessary obstacle before the product launch.

But Just How Necessary is API Virtualization?

All things considered, API service virtualization remains essential to testing. If you save up for virtualization and do some extra testing with it, it could be immensely rewarding to your company. Here are the reasons why.

The Virtualization Increases the Gains of API Mocks

The progress achieved in the mocking phase can be compounded by virtualization. One example is how virtualization can curb the spread of “false positives” in mock testing. Testers may be led into a false sense of security when individual mocks all yield their desired outcomes. The virtualization can help them see beyond that and realize bigger-picture concerns in the API.

It’s Worth the Investment

Yes, the initial cost for a service virtualization will be hefty. But it could save you from bigger expenses in the long run. If the virtualization can help you launch a stable, high-performing API product, you’ll be shortening its time to market. You’ll also be spending less on debugging and remedying downtime.

It Helps Craft a High-Quality and Integrable API

While API mocking should be for testing individual calls, API service virtualization is more for quality assurance. This last step should gear testers toward fine-tuning the product and making sure it is integrable. Virtualization will shift the focus on client integration in the way that mocking testing cannot. Therefore, it’s really best that you dedicate time to testing with an API service virtualization.

Conclusion

Mocking is a critical step in the API testing process, but mocking alone will not suffice. Acquiring an API service virtualization will be much better for the end product than exclusive mock testing. Don’t limit your testing to mocks, and expand your testing process to include an API service virtualization.