API Testing and API Test Tools

To discuss API testing and the tools involved we need to first describe what we mean by API.

Wikipedia defines API as set of functions and procedures that allow the creation of applications which access the features or data of an operating system, application, or other service and API testing as a type of software testing that involves testing application programming interfaces (APIs) directly and as part of integration testing to determine if they meet expectations for functionality, reliability, performance, and security.

API which means  Application Programming Interface, that specifies how one component of an application should interact with the other. It consists of a set of  protocols routines and tools for building the software applications. It enables an interface for connection between two systems.

What is an API Testing?

At sharptester.com we define API testing as a test that is performed to confirm that API’s executes successfully, return the correct value when executed based on the input conditions, update any data structure as expected and also triggers some other event or calls another API.

What You Need to start API testing

1. Who is your target audience? Who is your API consumer?
2. What environment/s should the API typically be used?
3. What aspects are you testing?
4. What problems are we testing for?
5. What are your priorities to test?
6. What is supposed to happen in normal circumstances?
7. What could potentially happen in abnormal circumstances?
8. What is defined as a Pass or a Fail? What data is the desired output? What is the chain of events?
9. What other APIs could this API interact with?
10. Who on your team is in charge of testing what?

After these testing boundaries and requirements have been created successfully,  it is mandated to determine what you want to test your API for. Below are some examples

• Functionality testing — This is to validate that the API works successfully
• Usability testing —This is to validate that the API is easy to work with.
• Reliability testing — This is to validate that the API can beconnected to and  provide consistent results.
• Load testing — This is to validate that the API can handle a large amount of calls at the same time or over a period of time.
• Security testing — This is to validate that the API has defined security requirements including authentication, permissions and access controls. See some API security tips for protecting vital data.

Here are some of the common API test examples:

• Validating that API return values based on the input conditions.
• Verifying if the API doesn’t return anything at all or the wrong results.
• Verifying if the API triggers some other event or calls another API.
• Verifying if the API is updating any data structures.

Some Open Source API Testing Tools For REST & SOAP Services

• Postman
• Karate DSL
• SoapUI 
• HttpMaster
• Rest-Assured
• RestSharp
• hippie-swagger 
• WebInject
• PyRestTest
• Airborne
• Unirest
• Mockbin

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