How to use postman for testing

Postman is a popular API development and testing tool that allows developers to design, document, test, and monitor APIs. Here’s a wider look at what Postman is, its key features, and how to effectively use it for various purposes.

What is Postman?

Postman is a collaborative platform for API development, enabling developers to:

ü  Design APIs: Create and manage APIs, define endpoints, and set up requests/responses.

ü  Test APIs: Send HTTP requests and view responses directly in the interface.

ü  Document APIs: Automatically generate documentation for your API endpoints.

ü  Mock APIs: Create mock servers to simulate API behavior without deploying the backend.

ü  Monitor APIs: Set up monitoring to test API performance and uptime.

ü  Collaborate: Share APIs, environments, and collections with teams for improved collaboration.

Key Features of Postman

1. Request Building:

ü  Supports HTTP methods such as GET, POST, PUT, PATCH, DELETE, etc.

ü  Allows adding headers, query parameters, request bodies, form data, and authentication methods (Basic, OAuth, Bearer Tokens).

ü  Can test REST, SOAP, and GraphQL APIs.

2. Collections:

ü  Organize your API requests into collections (groupings of requests). You can categorize requests based on environments, projects, or API functionalities.

ü  You can run entire collections sequentially using Collection Runner.

3. Environments:

ü  Create environments (like development, staging, production) to manage variables for URLs, tokens, and other request-related data.

ü  Environments allow switching between different configurations, ensuring flexibility in testing.

4. Variables:

ü  Postman allows setting global, environment, collection, and local variables that can be reused across requests. These can store dynamic data like tokens, IDs, or any values required across requests.

5. Pre-request and Test Scripts:

ü  You can write JavaScript pre-request scripts to execute before sending a request (for things like generating tokens, setting headers).

ü  Use test scripts to validate responses, check for status codes, response time, or parse JSON/XML for values.

ü  Built-in libraries like Chai.js for assertions make it easy to write automated tests.

6. Response Validation:

ü  Postman lets you view responses, including headers, body, status codes, and time taken for requests.

ü  Visualization: Convert the response data into custom visual representations (charts, tables, etc.) for easier interpretation.

7. Automation:

ü  Use Collection Runner to run multiple requests in sequence.

ü  Postman supports Newman, a command-line tool, for running collections in CI/CD pipelines and other automated systems.

8. API Documentation:

ü  Automatically generate and host API documentation from your collections. This is useful for sharing APIs with external developers or internal teams.

ü  Postman provides a public or private link to the documentation.

9. Mock Servers:

ü  Create mock servers to simulate endpoints before the actual backend is ready. This allows testing front-end or other components without depending on the live server.

10. API Monitoring:

ü  Set up monitors that run scheduled tests on your APIs to track uptime and performance metrics.

ü  Monitors can be set to run on specific intervals and provide detailed analytics for your API's health.

11. Integration with Version Control:

ü  Postman integrates with GitHub, GitLab, and other version control systems, allowing versioning and collaboration on collections.

12. Team Collaboration:

ü  Teams can share requests, collections, environments, and more in Postman. It also supports commenting and reviewing within the platform.

ü  Workspaces: Create team-specific workspaces where collections and APIs can be shared with members.

13. Postman API:

ü  Postman provides its own API to manage collections, environments, monitors, and more programmatically.

How to Use Postman for API Testing

1. Building a Request:

Ø  Choose the HTTP method (e.g., GET, POST).

Ø  Enter the API endpoint URL.

Ø  Add headers or query parameters if necessary.

Ø  For POST or PUT requests, add the request body (JSON, form-data, etc.).

2. Using Pre-request Scripts:

Ø  Example: Add a Bearer token to every request using a pre-request script.

javascript

pm.request.headers.add({     key: "Authorization",     value: "Bearer " + pm.environment.get("accessToken") });

 

3. Writing Test Scripts:

Ø  You can write test scripts to validate responses. For example:

javascript

pm.test("Status code is 200", function () {     pm.response.to.have.status(200); });   pm.test("Response time is less than 500ms", function () {     pm.expect(pm.response.responseTime).to.be.below(500); });   pm.test("Check if JSON response contains a specific key", function () {     var jsonData = pm.response.json();     pm.expect(jsonData).to.have.property("name"); });

 

4. Running Collections:

Ø  Use the Collection Runner to run a series of API requests in a specific order.

Ø  Set iterations, delays between requests, and export results as reports.

5. Automating with Newman:

Ø  You can run Postman collections from the command line using Newman.

Ø  Install Newman using npm:

bash

npm install -g newman

 

Ø  Run a Postman collection:

bash

newman run your-collection-file.json

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Advantages of Postman

Ø  User-Friendly Interface: Easy to use, even for beginners.

Ø  End-to-End API Development: From design to testing, monitoring, and documentation.

Ø  Collaboration: Teams can easily work together on API development and testing.

Ø  Wide Range of API Support: REST, GraphQL, SOAP, and other protocols.

Ø  Extensive Documentation & Community: Huge ecosystem of plugins, templates, and learning resources.

Disadvantages

Ø  Heavy Interface: For larger collections, Postman may become slow or resource-heavy.

Ø  Limited Testing Flexibility: While it covers basic automation, more complex testing scenarios might require dedicated testing frameworks.

Conclusion

Postman is a powerful tool that covers the entire lifecycle of API development, from designing APIs to testing and monitoring them. Its wide feature set, collaboration tools, and automation capabilities make it indispensable for API developers, QA testers, and DevOps engineers.

With Postman, you can ensure your APIs are robust, well-documented, and thoroughly tested, leading to faster development and more reliable software.