Define an API Testing with Tools and Challenges

What is an API?

Application Programming Interface (or API) is a set of rules, methods, and protocols for accessing a web-based software application as well as mobile based application and used by an individual program to communicate with one another directly and use each other's functions to get information.

In other words, it’s a way for different software components to interact with each other.

In general API's, We are used server name, path:

http://<server name>/v1/export/Publisher/Standard_Publisher_Report?format=csv

What is API testing?

• The API Testing is performed for the software application, which has a collection of API that must be tested.
• You use a software application to send calls to the API, get output, and note down the system's response while performing the API testing.
• API testing requires the Back-end/Database testing, you may have a brief knowledge of SQL queries.

Why Back-end /Database?

When you test the API, you may not aware of GUI of the application. So DataBase is only the way to cross-check, you are doing right or wrong.

(As we cross-check with the database if you know basic SQL queries ( SELECT, UPDATE, ALTER, DELETE ) that would be the advantage.

What is API Architecture?

API calls include three things:

1)  HTTP headers  - HTTP headers depend on your application, Focus on mainly 2 points:

1. Authorization - A token and header require to identify the requester.
2. Content-Type - It describes the response of the request in application/json format.

2) HTTP Request  -  We are the focus on four requests, which we are used:

1. GET- While using the GET method, it retrieves the information from the given server with a given URI and it doesn’t effect on the other data.
2. POST- This request is used to create a new entity. It can also be used to send data to the server, for example, create attendance, customer information etc.
3. PUT- This method helps to create a new entity or update an existing one.
4. DELETE- This method is used to remove all target resource given by a URI.

3) Status Code/Response Code - We can verify the response from the many status/response code. There is following response code:

What is API Testing Tools?

3 popular API test-tools:

Postman is a simple tool for sending the HTTP requests in an easy way and is a more powerful tool used to test the web services.

Curl is a command-line tool and used the multiple HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, LDAP, DAP, DICT, TELNET, FILE, IMAP, POP3, SMTP and RTSP protocols to deliver the requests.

SoapUI is a free tool used to test Web Services for both SOAP and RESTful.

What are Challenges of API Testing?

Challenges of API testing includes:

1. The main challenge is Parameter Combination and Selection and Call Sequencing
2. There is no GUI available to test the application which makes difficult to cross-check, you are doing right or wrong with given input values.
3. The little bit difficult to validate and verify the output in the different system for testers.
4. Parameters selection and categorization requires being known to the testers for API testing.
5. Exception handling function requires being tested.