Getting Started with Postman API Testing

Postman is an API(application programming interface) development tool that helps to build, test and modify APIs. Almost any functionality that could be needed by any developer is encapsulated in this tool. It is used by over 5 million developers every month to make their API development easy and simple. It has the ability to make various types of HTTP requests(GET, POST, PUT, PATCH), save environments for later use, converting the API to code for various languages(like JavaScript, and Python).

Prerequisites:

• Postman Application downloaded on your machine
• Knowledge of CRUD operation

Why API Testing is Important ?

API testing is important for ensuring the functionality, reliability, and security of software applications. By validating API functionality, testing promotes bug-free operation and prevents errors. It guarantees the stability of APIs under every condition and safeguards data integrity and security that is crucial for handling sensitive information.

Furthermore, API testing ensures compatibility, optimizing performance and compliance with regulatory requirements. Ultimately, it enhances the overall quality, reliability, and security of applications, thereby improving the user experience and minimizing risks associated with software development and deployment.

Why use Postman ?

• Free: Postman is a software program that we will use for API testing. It is easy to download and use for groups of any size.
• Easy to use: Postman is an easy-to-use software program tool. We can do HTTP requests of many types (together with GET, POST, PUT, PATCH, etc.).
• Community and Support: It has a large network discussion board for customer service and huge documentation.
• API Support: It enables us to make any API call (REST, SOAP, or undeniable HTTP) and effortlessly look into even the biggest responses.
• Integration: Postman enables our capacity to effortlessly combine check suites into our favoured CI/CD equipment and services, together with Jenkins with Newman (a command-line series runner).

Steps for testing API on Postman

Step 1: After downloading and signUp you will see a dashboard. Click on the WorkSpaces and after that click on new collection.

Step 2: Name the collection according to your choice and after that on the right hand side of the collection name, click on 3 dots and select Add request option.

Note: We will be using sample API for testing.

https://jsonplaceholder.typicode.com/posts/1

Step 3: Click on Tests. Now in the right side pane, we can multiple snippets arrived. We can use any of the available snippet/test or create our own test based on our requirement. Code is written in JavaScript.

Step 4: We will write 2 Tests in JavaScript from the already available snippets from the right-hand side pane.

First Test: This will check whether the response time is less then 200ms

pm.test("Response time is less than 200ms", function () {
    pm.expect(pm.response.responseTime).to.be.below(200);
});

Second Test: This will check whether status code is 200

pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

Step 5: After that click on send button to send the request. We will see in the output terminal the results of the Tests.

By following these steps you have successfully tested your API.