Skip to content
Postman API Testing Tips

How To Automate Api Using Postman

API Testing Blog

Automating API Testing with Postman

Postman is a powerful tool for interacting with APIs, and it also offers robust features for automating API testing. This guide will demonstrate how you can leverage Postman to automate your API testing process, improving efficiency and reliability.

1. Setting Up a Postman Collection

A Postman Collection is a container to organize and manage your API requests. This is essential for automating your tests.

  • Creating a Collection: Click on the “Collections” tab in Postman. Then click on the “Create Collection” button and give your collection a descriptive name (e.g., “My API Tests”).

  • Adding Requests: Within your collection, create new requests by clicking the ”+” button (or “Create Request” in the dropdown). Add request details like:

    • HTTP Method: GET, POST, PUT, DELETE, etc.
    • URL: The API endpoint URL
    • Headers: Key-value pairs for authorization, content type, etc.
    • Body: The request data in JSON, XML, or plain text formats.

Example:

Let’s assume we’re testing an API that fetches a user’s details.

Request:

{
  "method": "GET",
  "header": [
    {
      "key": "Authorization",
      "value": "Bearer your_token"
    }
  ],
  "url": "https://api.example.com/users/123"
}

2. Building API Test Scripts with Postman’s Runner

Postman’s Runner allows you to execute your API requests and include test scripts to verify the API’s behavior.

  • Adding Tests: In each request, navigate to the “Tests” tab. Here, you can write JavaScript code to perform assertions and checks.

Example:

// Check if the response status code is 200 (OK)
pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});


// Validate the response body
pm.test("Response has user ID", function () {
    pm.expect(pm.response.json().id).to.be.equal(123);
});

3. Implementing Parameterization for Flexible Testing

Parameterization allows you to execute the same test with different input values, making your tests more comprehensive and flexible.

  • Using Environment Variables: Postman’s environment variables allow you to store dynamic values such as URLs, API keys, or data for your tests. To define environment variables, go to the “Environments” tab, create a new environment, and add your variables.

Example:

Environment:

  • Variable Name: base_url
  • Variable Value: https://api.example.com

Request URL:

  • {{base_url}}/users/123

  • Using Collection Variables: Collection variables are specific to a particular collection. You can define these within your collection settings.

Example:

Collection:

  • Variable Name: user_id
  • Variable Value: 123

Request URL:

  • {{base_url}}/users/{{user_id}}

4. Leveraging Postman’s Test Runner for Automated Execution

The Postman Runner allows you to run your collection of requests with defined tests in an automated manner.

  • Running Tests: Click the “Runner” button within your collection. You can select your environment, iterations, and other settings.

Example:

  • Environment: “Production” - This environment contains production-specific API credentials and URLs.
  • Iterations: 5 - The tests will be executed 5 times.

This will run the collection, execute the tests after each request, and display the results in the Runner tab.

5. Generating Reports for Comprehensive Analysis

Postman offers features to generate reports of your automated API tests.

  • Generating Reports: Postman provides options to generate reports in various formats (e.g., HTML) after running your tests. These reports can be used to track test results, identify failures, and analyze trends.

6. Integrating with CI/CD Pipelines for Continuous Testing

Postman integrates seamlessly with CI/CD pipelines, allowing you to automate API testing as part of your development workflow.

  • Using Postman CLI: The Postman command-line interface (CLI) allows you to execute tests within your CI/CD pipeline. You can trigger your tests through scripts in your CI/CD tool (e.g., Jenkins, GitLab CI).

Example using GitLab CI:

stages:
  - test


test:
  stage: test
  image: node:latest
  script:
    - npm install -g newman
    - newman run collection.json -e environment.json
  • Using Postman API: Postman’s API enables you to programmatically control and interact with Postman’s features within your build scripts.

By integrating your automated API tests with CI/CD, you ensure that every code change is thoroughly tested, enhancing the overall quality and reliability of your application.

7. Advanced Features for Sophisticated Testing

Postman provides advanced features to enhance your API testing capabilities.

  • Using Data Files: Postman allows you to import data from external files like CSV or JSON. This is useful for parameterizing your tests with a large number of data sets.

  • Using Mock Servers for Offline Testing: Postman can create mock servers that provide simulated responses to your requests, even without real-life APIs. This enables offline testing and facilitates development scenarios where the actual API might not be ready.

  • Using Monitors for Continuous Monitoring: Postman Monitors allow you to execute your API tests at regular intervals. This enables continuous monitoring of your API endpoints and proactively identifies issues.

Conclusion

Automating API testing using Postman empowers you with a robust testing framework that improves efficiency, reliability, and overall quality of your software applications. By leveraging the features discussed in this guide, you can streamline your API testing process, catch issues early, and ensure that your APIs function as expected.

API Testing Blog