Understanding the Importance of Mocking API Callbacks

In the parlance of API development, callbacks are asynchronous outgoing requests that result in one service being made out of another service. For those who are yet unfamiliar with the idea, a simple comparison that can be made to API callbacks are self-addressed sealed envelopes (SASEs). When you send a SASE, you’re asking your letter’s recipient to respond to you using that same envelope.

An API callback functions just like that envelope: it is an action that demands a response in a similar way. And like other API-related processes, callbacks can be mocked—or imitated for the purpose of testing a certain API behavior—in open environments. For those who are curious about the need to mock API callbacks, here’s a briefer on why the process important when you are using open API mocking resources.

The Logic behind Executing a Mock Callback

Developers actually do have the option of not mocking callbacks in an open environment. They also have the choice to test on a live API, for example by using a library to make HTTP requests from a network. But the fact is that there are certain risks to tinkering with the actual API. Take the example of wanting to test for an API that’s been completed, and whose features may only need to be updated. In this situation, you risk bringing in some potential problems when you are introducing new and untested code.

What does this mean? This means that you’ll have to survey problems in the API all over again in order to fix them. Consequently, you may be backtracking on your previous progress with the API.

Thus, it’s in your best interest to test something as important as your API’s callbacks. The best practice that any beginning developer should subscribe to is to test a mock callback in a mock server. That way, any API tester doing mock callbacks will do so in a controlled environment with fewer stakes. This is also the perfect environment for the API team to clearly see what’s going right—and what’s going wrong—

with the API. That option provides optimum control, minimizes pressure, and reduces risk on behalf of a developer studying the callbacks. This is a much better alternative than potentially interfering with the live API.

Conclusion: How to Make the Best Out of Your API Mock Callbacks

Now that you understand the rationale of mocking callbacks, what are some tips that will help you do so in an open environment? Here a few that will surely prove useful.

• Choose a test framework that suits your purposes. Python, Jasmine, and Jest are all popular frameworks for mocking API callbacks. Each has their own set of pros and cons. See which one feels comfortable for you and adheres to your API development goals.
• Know which calls to make and what outcomes to expect. It’s good to compile a list of all the important callbacks you need to mock, as well as the outcomes you should expect. Make sure you have this list on hand when it’s time to commence mock testing.
• Afford callback mocking an important place in your API documentation. Any time you deploy a mock, note it down in your existent API docs. Alternatively, if you don’t have working API documentation yet, your mock testing agenda should be a good enough excuse to start on your docs.

Mocking callbacks to test desired responses is a fruitful and valuable process. So be wise in your API development process. Don’t skip out on mocking callbacks or any other vital component of your API. Doing rounds of extensive and accurate testing is the key to a successful API product. Check out this list of APIs (which are free to use) if you’re looking to continue your testing.