Mocking Helps You Get It Right the First Time

Danielle Gaither
by Danielle Gaither on March 10, 2023 6 min read

Dev teams are always looking for ways to do more with less, and one of the best ways to achieve that goal is to avoid wasted effort. To that end, mocking can be an effective way to help dev teams save both time and money.

How does mocking help? Untested API designs can leave a lot of flaws in your application, including security vulnerabilities and inefficient use of local and external resources. These flaws, when undetected, can lead to higher operational costs—and that’s before factoring in the time and labor needed to fix them. Thorough testing of your API designs is necessary to ensure that the reliability, security, and performance of your code is where you want it to be, even if doing so requires a little more time upfront. The Rule of Ten, which states that the cost to fix a bug increases tenfold with each stage of the development process it passes through, puts a premium on addressing API issues early.

Fortunately, mocking can help you avoid the problems of untested API designs. Mocking is especially important for validating your code—ensuring that you’re building the product that you actually intend to build. And the benefits of mocking aren’t limited to testing. By the end of this article, you’ll have a better grasp of what mocking is, some of its pros and cons, and how you can apply it in every phase of the software development lifecycle.

What Can (or Can’t) Mocking Do for You?

For the purposes of this article, mocking means setting up one or more mock servers in order to test your API. But why would you want to go to the trouble of setting up a mock server? Wouldn’t it be better to test against real servers to ensure your responses match your users’ experience?

There are a few reasons you might not want to go that route, especially in earlier phases of development:

  • Production data might not be available or reliable.
  • You might not want to touch production servers at this stage.
  • Real API calls might cost money that your team prefers to save for production use.
  • Your production application might have a lot of external dependencies that could have unintended effects during testing.

However, like any tool, mocking isn’t the solution to every problem. One of mocking’s limitations is potential code duplication, which developers generally prefer to avoid. Another concern is that mocking doesn’t provide much information about integration between different components of your application, as most of those components are abstracted away as part of the mocking process. So before setting up a mock server, ensure that it’s a fit for the problem you’re actually trying to solve.

Solve Your Pain Points with Mocking

So far we’ve talked about mocking as part of a larger testing strategy, but that isn’t the only time when it can be beneficial. Mocking can help reduce development costs at any phase of the software development lifecycle—read on to see the benefits of mocking in every phase.

Planning and Analysis

Even before you start writing your code in earnest, using a mock server for a prototype can help you get valuable user feedback. While you can learn some things from HTML mockups or even paper representations of your app, mocking can provide your users something that looks and feels more like the real thing. Working with a mock server–backed prototype gives you much more UX design information than static mockups or fixed interactions. This kind of testing also provides more realistic insights on how users might interact with your product.


Design rarely takes place in a vacuum. Real-world applications often have to interact with a lot of external code. Mocking can help by ensuring that your application’s business logic works as intended before you get too deep into creating the user interface. This blog post from Codurance uses an e-commerce example to illustrate how you might use mocking in your design process. If you want to keep your designs in line with the OpenAPI standard, Stoplight has the tools to help you make that happen.

Development and Testing

While you’re developing and testing your application, mocking can help you ensure that the application is staying on track with the design goals you set earlier. And as previously discussed, mocking can be an integral part of the testing process, even if it shouldn’t be your entire testing strategy. For more information on using mocking as part of your testing plan, check out our article on how mocking and other testing can improve the developer experience.

Integration and Implementation

As helpful as mocking can be in creating a product, it’s no substitute for having real users use the real thing. This phase is where many teams tend to be increasingly concerned about real-world performance. But even in this phase, mocking can help with debugging your code before it goes into the final stages of delivery. That way you aren’t wasting your labor and other deployment resources on code that you’re not confident in.


One of the biggest challenges of code maintenance is the risk of introducing breaking changes. Fortunately, mocking can save a lot of time and effort here, too. One way mocking can help with code maintenance is by ensuring that any interactions between dependencies work as they should. Another benefit of using mocking as part of your maintenance workflow is that it allows testers to preview the upcoming changes to see how their code might be affected. Taking these steps before pushing your update contributes to a smoother experience for all involved.

It’s No Joke! Mocking Saves Time and Money

Now that you have a better understanding of what mocking is and how to make it work for you in every phase of the software development lifecycle, what comes next? Signing up for a free Stoplight account gives you access to our helpful API design tools, including OpenAPI-powered mock servers and our open-source mock HTTP and proxy server. You also get a wealth of documentation on how to use these and other tools most effectively, including our comprehensive API mocking guide. Get started today!

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