If you’re a junior tester looking to enhance your skills or a more experienced professional wanting to refresh your knowledge, you’ve come to the right place!
In this article, we’ll dive into what API testing is, the tools you can use, and how you can get started with it.
What Is API?
Let’s start with the basics. API stands for Application Programming Interface. In a typical application, there are three main layers: the presentation layer (the UI), the service layer (the API), and the data layer.
The API sits in the middle, acting as a bridge between the presentation and database layers. It enables communication and the exchange of data between two separate software systems.
What Is API Testing?
API testing is a type of testing that validates the API. Its purpose is to check the functionality, reliability, performance, and security of the programming interface. As part of integration testing, API testing validates the logic of the build architecture within a short period of time.
Benefits of API Testing
Here are some of the top benefits of API testing:
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Language Independent: APIs communicate using formats like XML and JSON, which means that API testing can be done with any programming language.
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Easier Test Maintenance: Unlike UIs that change frequently, API changes are more controlled and happen less often, making test maintenance easier.
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Improved Test Coverage: Since most APIs or web services have specifications, you can develop automated tests with high coverage that ensure most use cases are tested.
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Time Efficiency: Compared to GUI testing, API testing is much faster. For example, while a UI test might take 7 minutes to run, an API test only takes about 12 seconds.
Types of API Testing
API testing can cover several types of testing. Here are the main types:
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Review the API Specification
Before starting, familiarize yourself with how the API works and what to expect when using it. -
Determine API Testing Requirements
Understand the target consumers, the API’s features, functions, workflow, and priorities. This helps in crafting effective test cases. -
Define Input Parameters
Configure the database and server to meet the application’s specific requirements. -
Create Positive and Negative Tests
Conduct both positive and negative tests. Positive tests verify functionality, while negative tests check how the API handles incorrect inputs or unauthorized actions. -
Select an API Testing Tool
Once you’re comfortable with the concept of API testing, the next step is to pick the right tool for your project.
The Top 5 Tools for API Testing
Deciding what tool to use is a hassle on its own. To make it easier, we’ve prepared a list of 5 tools that can be used for API testing. However, when working on a project, you should choose a tool with a programming language the developers are already using:
Postman is an API platform for building and using APIs. It serves as an HTTP client capable of both automated and manual testing, allowing you to autopilot routine tests while you try specific use cases.
SoapUI is a functional testing tool for SOAP and REST testing. It has an easy-to-use graphical interface that allows you to create automated functional, regression, and load tests.
The tool comes in two variants, SoapUI Open Source, a free tool, and ReadyAPI, a paid tool. ReadyAPI provides more options to construct, deploy and monitor your tests than SoapUI Open Source.
Katalon Studio appeals to users looking for a more comprehensive solution for deployments across multiple platforms. It combines manual and automated testing for web, desktop, and mobile applications.
JMeter was initially intended for API load testing, but it can now handle performance testing. You can test performance both on static and dynamic resources.
Rest Assured is a free, open-source testing tool. It is a Java library that streamlines HTTP requests to REST APIs.
API is considered the engine of the application and should work as expected without errors. To ensure they meet functionality, performance, security, and reliability expectations, APIs must undergo API testing.
Why is API Testing Important?
APIs are the engine that drives applications, which means they must work as expected; without errors. API testing ensures that the API meets the functionality, performance, security, and reliability requirements. Inadequate testing can lead to issues down the line, affecting the overall user experience and application performance.
By performing thorough API testing, we can ensure that the software operates smoothly, performs optimally, and delivers the expected results to end users.
Conclusion
To wrap it up, API testing is an essential part of the software testing lifecycle. It ensures that the core functionality of an application works as expected, without relying on the user interface. API testing is faster, more efficient, and gives you more control over the testing process.
If you’re looking to get started with API testing, the tools mentioned above will serve as a great starting point. Whether you’re testing a simple API or a complex system, the right tools and understanding will set you up for success.
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