Types of API Testing

Application Programming Interface (API) enables the communication and data exchange from one software system to another. API testing is a software testing practice that tests the APIs in terms of functionality, performance, Security etc.

Benefits of API Testing

The main benefits of API testing includes but not limited to,

• Language independent

• GUI independent

• Improved test coverage

• Faster releases

Types of API testing

There are different types of API testing which are listed below:

1. Validation testing

2. Functional testing

3. Load testing

4. Security testing

5. Runtime/Error Detection

6. Penetration testing

7. Fuzz testing

8. Integration testing

1. Validation testing

Validation testing occurs at the final step and verifies whether the API is working as per the given requirement. It verifies the product and behavior aspects and the successful validation testing indicates the assurance of correct development.

2. Functional testing

Functional testing is a key testing process which tests specific functionality within the code base. It includes verification of keys, values, required and optional fields, structure of JSON/XML, responses, request and header information.

Functional testing ensures that the API actually works within the expected parameters. It verifies that the API returns the expected output for the given input and ensures it handles the errors when the results are outside of the expected parameters.

3. Load Testing

Load testing will ensure that the API responds to all of the requests sent by the various servers at the same time. In other words, Load test will check how the APIs are handling, for example if 10 requests per second are sent to the API. Generally, the validation of load testing is done by artificially creating or simulating API calls.

Load testing will monitor the APIs performance at both normal and peak conditions.

4. Security Testing

Security testing validates whether security requirements are met or not. This includes authentication, permission and access control and also verifies that no more than the required data is shared. It ensures that the API implementation is secure from external threats and also does validation of encryption methodologies.

5. Runtime/Error Detection

Runtime/Error detection is done to check whether the APIs detect the error and throws error message when invalid scenarios like Invalid requests, Null or Empty request are given. It focuses on various aspects like monitoring, execution errors or error detection.

6. Penetration Testing

Penetration testing focuses on the verification of security vulnerabilities that an attacker could exploit like SQL injection or any other attack to fetch the secure resource. Usually, users with limited API knowledge will try to assess the threat from an outside perspective which aims the entire API or its components.

7. Fuzz Testing

Fuzz testing is one of the important steps in security audit process where invalid, unexpected, or random data are provided as inputs to a computer program to detect any forced crashes or negative behaviors. This technique tests the API’s to prepare for the worst-case scenarios.

8. Integration Testing

Integration testing is done to check how API’s are behaving after they are integrated with the UI Layer. It ensures that all the APIs connected to each other communicates properly by validating the flow of data and information between the API connections. It also validates the addition of any features in the API do not cause bugs in other API modules. It provides an overview of the usability and efficiency of the APIs at the front and back end.