In the field of software test engineering, API testing is one of the most important and sought after requirements for any application or system.
This article covers:
Functional testing of an API is done to validate the correctness of the API response for a given request. For any given method, API response is what needs to be validated. Response is not only the response body, but also the returned status code.
Many times an API is meant to call another API or trigger another action. In these cases, performing an overall call sequencing and validating them at the same time would be considered as integration testing.
As the name suggests, security testing of APIs deals with the security of the API under test. Let it be about who is calling the API (client or other application), can the requested data be manipulated before reaching the server, and the response data be securely transferred to the requesting party? It is about validating the implemented security mechanisms like Basic Authorization, OAuth or two-way authentication.
Performance testing of an API is performed in various scenarios depending on the requirements.
In all these scenarios, it is vital to keep an eye while monitoring the responsiveness of the APIs for the part that is causing issues. End goal is always to figure out these issues, fix them, retest the same scenarios for the fixes and repeat until it is considered satisfactory.
There are many different protocols available, but most widely used and accepted ones are:
Representational State Transfer (REST) is a web architecture concept, which represents the current state of the requested resource. Client or requesting entity makes a logical request with the required data for a specific resource to the server; the server then responds with the current state of the resource without keeping or storing any information of the request.
REST follows these rules strictly
Descriptions about these constraints can be referred here.
Simple Object Access Protocol (SOAP) is a messaging protocol for web services. It uses XML to handle the request and response. SOAP is a neutral and extensible protocol available for any programming language and other protocols such as HTTP, SMTP etc.
Available methods for API testing are:
There are other methods available, but the ones mentioned above are the most used.
The biggest challenge in API testing is the psychology of the people who have not yet done it or just started to do it. Making a shift from testing UI based components to API creates a psychological fear that it is too technical in nature. Maybe because it doesn’t give the comfort of an interacting GUI and things happen at the back end.
All it requires is a basic conceptual knowledge of the client-server architecture. Web services functioning and a very good understanding of the system under test.
Most of the time, documentation for the APIs under test is either unavailable or not exhaustive. It fails to provide the relevant and required information to the tester. This leads to a lesser confidence in the tester even if the test coverage is fairly good.
Things are happening at the backend and the tester is relying only on the response data. What happened and why it happened is not clear or not seen at least. Imagine having server logs where the tester can see the action happening and build confidence just by knowing what happens when she makes a simple API call.
The market is flooded with myriad API testing tools. It is not easy to find out the best suited tool for your context. POSTMAN is one tool which is proven to handle almost everything. Better to go with it than experimenting with others.
Write to [email protected] for API testing services and automation solutions.