APIs are a type of protocol used to communicate between applications on different computers or mobile devices. One or more virtual machine environments (VMS manage the protocol) provide the API application servers. An API is an application programming interface (API), also known as a protocol or message format. It is defined in RFCs and can be implemented by any application using standard programming interfaces.
The Internet has been growing exponentially for the past ten years. This has led to an explosion in the number and variety of applications on offer. It is easy to get carried away by the ever-growing potential of an API. Too often, though, applications built on top of APIs suffer from poor APIs—or lack of attention to their quality—resulting in poor user experiences and increased costs when using them. The Web API Project aims to encourage the creation of stable, dependable, well-tested APIs on the web. These will become the standard for all future websites.
If you are developing an API, you must make it testable. API testing becomes more critical as your API grows in complexity and use. Every new API is like a new test. You want to make it as easy as possible for others to call your API, but limits and edge cases need to be considered. If your end goal is maintainability, testable APIs are best.
Two factors decide if an API is good. Is it a general-purpose interface for a service that anyone can use? And does it allow the client to control the service remotely? If the API provides limited functionality but is general purpose and allows remote control, it is almost guaranteed to be good. If it provides limited functionality, the client can interact with it via the browser (and therefore has an established user interface). It probably means that the author has not taken the time to implement security measures. This article discusses various ways of testing your API.
Unit testing
We’ve arrived when the WebWeb is saturated with hundreds (perhaps thousands) of different products, all of which promise to improve your life. And yet, testing is still an infrequent activity among developers.
Web APIs are notoriously challenging to test. To make things worse, each recent version of the web API requires its developers to make recent changes, which means they’re not always aware of regressions until it’s too late. Developer acceptance testing (aka acceptance release) is a best practice for making sure your web services work with alternative versions of web API without causing breakage. It ensures your users have a consistently exceptional experience when using your services.
It is essential to do unit testing with web APIs. There are two reasons: first, this helps you find and fix problems before they become critical; second, it helps you understand how the API works and provides insight into how other applications might use it.
For example, in a typical web API application, you might have a client that requests a particular record from the server, and you should be able to respond with the data. However, if the request is invalid (for example, if the client provided an invalid IP address), you will receive an invalid request.
End-to-end Testing
End-to-end tests ensure that a web API received by a client does not change dramatically before the request is handled. When an API change occurs, an HTTP request using the old API should be matched against the corresponding request using the new API; if there is a mismatch, an error will be returned.
If the new data matches what we expected to be received, everything proceeds as though the request had been made using the old API. This allows end-to-end tests to be conducted as early in the development cycle as possible before any changes have been made to any of the microservices that make up the application.
There’s an abundance of open source web APIs and frameworks out there. With so many options, it’s challenging to figure out which ones are worth adding to your stack. Besides readability and maintainability, there are other benefits to using end-to-end tests – such as better feedback during development.
Integration Test
API integration testing involves a series of processes to ensure that any issues encountered in using the API are reproducible and can be identified and resolved before critical functionality is exposed to the public. This can include testing the end-to-end solution using the latest version of the application, running load tests on Nginx if an API is enabled through a CDN, and using Xdebug for early detection of XSS and other exploitable vulnerabilities.
Running integration tests on front-end APIs is essential, and it’s essential to do them right. API testing ensures that your application uses the given API correctly and against all combinations of client and server states. If an API can fail unexpectedly, then an application that relies on it will not work and may crash or become unresponsive. API integration tests are not just for code reuse—this is important for ensuring that notifications, messaging, context switching, and other interactions work as expected between applications that use the same data source.
It is common practice to mock up API endpoints in a separate browser tab and invoke them in the corresponding production code. This provides us with a way to validate that the service we are interacting with works as expected before creating another request.
The problem comes when creating such integration test scripts often fails because of insufficient testing of the underlying API. This is because API clients often return unfrequented tuples when calling a method on a virtual service.
Bottom Line
When a new API is released, there are many questions about how to use it correctly and whether it’s suitable for production. As a result, API testing has become an essential part of the software development workflow. When users use an application, questions need to be asked about how it works and its impact on its experience. Thus, API testing plays a vital role in keeping application development processes sustainable by ensuring that changes are revealed to users when they are needed most.
As outlined above, there are three ways to ensure your API functions as intended: unit testing, end-to-end testing, and integration testing. Unit testing is the least risky option, but it is the most expensive. End-to-end testing requires the developer to keep track of every call made to the API, but it can provide more reliable results in the unlikely case something goes wrong. Finally, integration testing allows you to make one call to an application using an existing endpoint and see what output that API returns without making a request. The best practice for all three is to make use of a stack trace when reporting issues to developers.