Using Postman Collections for Testing

Introduction

Postman is a popular API development and testing tool used by developers and QA engineers. One of its most powerful features is Postman Collections, which allow you to group, organize, and automate API requests for efficient testing.

Using collections makes API testing more structured, reusable, and scalable—especially for large projects.

What Is a Postman Collection?

A Postman Collection is a folder-like structure that contains:

API requests (GET, POST, PUT, DELETE, etc.)

Test scripts

Pre-request scripts

Variables

Documentation

Collections help teams organize APIs by feature, version, or workflow.

Why Use Postman Collections for Testing?

Organize API tests logically

Reuse requests and variables

Automate workflows

Run multiple tests at once

Share tests with team members

Integrate with CI/CD pipelines

Creating a Postman Collection

Open Postman

Click New → Collection

Name your collection

Add folders for modules or features

Add API requests inside folders

Best Practice:

Use clear naming conventions for collections and folders.

Adding Requests to a Collection

Create a new request and save it to a collection

Specify the HTTP method and endpoint

Add headers, parameters, and request body

Test the request manually before automating

Using Variables in Collections

Variables make tests flexible and reusable.

Types of Variables:

Global

Collection

Environment

Local

Example:

{{base_url}}/users

Best Practice:

Store URLs, tokens, and credentials as variables instead of hardcoding them.

Writing Tests in Postman

Postman uses JavaScript for test scripts.

Example Test Script:

pm.test("Status code is 200", function () {

pm.response.to.have.status(200);

});

pm.test("Response has user id", function () {

var jsonData = pm.response.json();

pm.expect(jsonData.id).to.exist;

});

Tests run automatically when the request is sent.

Using Pre-request Scripts

Pre-request scripts run before the request is sent.

Common uses:

Generate tokens

Set timestamps

Create dynamic request data

Example:

pm.environment.set("timestamp", Date.now());

Running Collections with Collection Runner

The Collection Runner allows you to:

Run all requests in a collection

Execute tests in sequence

Use data files (CSV/JSON) for data-driven testing

Best Practice:

Use the runner to validate full API workflows.

Automating API Testing with Newman

Newman is Postman’s command-line tool.

Benefits:

Run collections from the terminal

Integrate with CI/CD tools (Jenkins, GitHub Actions)

Generate test reports

Example command:

newman run collection.json -e environment.json

Sharing and Collaboration

Export collections as JSON

Share via Postman workspaces

Version control collections using Git

Add documentation directly inside collections

Best Practices for Using Postman Collections

Group requests logically

Use variables extensively

Write meaningful test assertions

Keep collections modular

Regularly clean unused requests

Use environments for different stages (dev, test, prod)

Conclusion

Postman Collections provide a structured and powerful way to test APIs efficiently. By organizing requests, automating tests, and integrating with CI/CD pipelines, teams can ensure API reliability and faster development cycles.

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