Testing APIs has a goal to check whether the APIs are perfect in terms of functionality, reliability, performance, and security. API testing must be done in several ways.
The unit is the smallest testable part of an application. It can be an individual program, function, procedure, or method. Unit testing verifies the functionality of a single operation and performed by using the White Box Testing method. Unit testing is the first stage in API testing.
Functional testing uses the Black Box method with no concern about the source code of the application. Fulfilling the following tasks conducts functional testing:
Understanding API Requirements
Creating Test data
Computing the outcomes of the input values selected for a test
Executing test cases
Comparing the actual and evaluated data
Functional testing is intended to verify that the application is functioning flawlessly.
Applications with poor performance can gain a low reputation and fail to meet business requirements. Performance testing determines API speed, scalability, and stability metrics under expected workloads. There are various subsets of Performance Testing:
Load testing exposes response time for each transaction; performance of the system and database components under different loads; network delay in the communication between the server and the client. Load testing detects design and server configuration issues, as well as hardware limitations
Stress testing carries under extreme workloads, such as under high traffic, to identify the breaking point of an application
Endurance testing ensures the capability of an application to handle the expected load over a long time
Spike testing exposes the behavior of an application with sudden large spikes in the load
Volume testing checks the performance of an application under varying database sizes
Scalability testing determines the effectiveness of an application under an increase in user load to plan capacity growth
Runtime Error Detection
Runtime Error Detection exposes critical defects that manifest at application runtime. An accurate detection report is an opportunity for efficiently identifying the root causes responsible for application breakdown, unpredictable behavior, and poor performance.
Security testing uncovers vulnerabilities, threats, risks by identifying possible weaknesses of the application. Security test results prevent malicious attacks from intruders, as well as the loss of information, revenue, and reputation.
Vulnerability Scanning executes automatically against known vulnerability signatures
Security Scanning can be performed both Manually and through Automated scanning to identify network and system weaknesses, and provide solutions for reducing these risks
Penetration testing simulates a malicious attack to check for potential vulnerabilities to an external hacking attempt
Risk Assessment analyses security risks and recommends appropriate controls and measures
Security Auditing inspects applications for security flaws and can perform line by line inspection of code
Ethical hacking intends to expose security flaws in the system
Posture Assessment combines Security scanning, Ethical Hacking, and Risk Assessments to show the overall security posture of an organization
Fuzz testing discovers coding errors and security loopholes by inputting massive amounts of random data, called fuzz
Interoperability and WS Compliance Testing for SOAP APIs
Interoperability and WS Compliance Testing is a type of testing that applies to SOAP APIs. Interoperability ensures conformance to the Web Services Interoperability profiles, WS Compliance testing ensures proper implementation and utilization of standards such as WS-Addressing, WS-Discovery, WS-Federation, WS-Policy, WS-Security, and WS-Trust.
Validation testing is one of the last and most important steps in the development process. Basically, it's a set of simple questions applied to the entirety of the project, including product validation, API behavior on accessing the correct data in the correctly defined manner; and the efficient opportunity for any codebase to be removed or altered to dispose of deteriorations in the general service.