API Testing in Software Testing
API Testing :
As we know API stands for Application Programming Interface which acts as an intermediate of communication between two applications. Due to this intermediary role of API (Application Programming Interface) two applications talk to each other and performs the required actions efficiently. API contains a set of rules and guidelines based on which the applications are developed. So in simple we can say an API acts as an interface between two software applications so that two software applications can communicate with each other.
The below figure represents an API in an application :
API Testing refers to test the APIs which are used in the application just to validate that the APIs are working fine. When a system has a collection of APIs, these needs to be tested to know that the system is working perfectly or not. Mostly we can say that API testing confirms system’s performance, reliability, security and functionality.
Below list represents some of the tools which are used for API Testing :
- Katalon Studio
- Soap UI
- REST assured
- Tricentis Tosca
- Ping API
GUI testing is different from the API testing as GUI testing is present at Presentation layer where the API testing is present at Business layer. If we will take an example of a typical app then API is the middle layer in between UI layer and Data base layer and due to this API communication and data exchange between the applications occur.
The below figure represents the layer at which API testing is performed :
API testing Types :
There are multiple types of testing which are most often used as form of API testing which means during multiple types of testing simultaneously API can be tested.
So below list represents the types of API testing i.e.
- Unit Testing
- Integration Testing
- End to End Testing
- Performance Testing
- Functional testing
- Security Testing
- Load testing
- Penetration testing
- Reliability testing
- Fuzz testing
What exactly we check during API testing :
- Data accuracy.
- Response time.
- Duplicate or missing functionality.
- Authorization checks.
- Multithreaded issues.
- Security and performance issues.
- Error codes if API returns.
- Reliability issues.
Benefits of API Testing :
Like we get a lot of advantages by using APIs in application, similarly by performing API testing we achieve a lot of things towards the success of the developed application. Below are some of the benefits i.e.
- Earlier validation of correctness in response and data.
- Earlier test maintenance.
- Better speed and coverage of testing.
- GUI independent testing.
- Reduced testing cost.
- Language independent test.
- Helpful in testing core functionality.