Environment variables in Postman - Build an Automation Script

Verify usage of environment variables in Postman request

Preconditions (2)

Step 1: Select the environment 'TestEnv' in Postman

Step 2: Create a new GET request with URL '{{baseUrl}}/posts/1'

Step 3: Send the request

Step 4: Observe the response status code and body

✅ Expected Result: The request is sent to 'https://jsonplaceholder.typicode.com/posts/1' and the response status code is 200 with a valid JSON body containing post details

Automation Requirements - Postman/Newman

Assertions Needed:

Verify response status code is 200

Verify response body contains userId, id, title, and body fields

Best Practices:

Use environment variables for base URLs and dynamic data

Use pm.expect assertions for validation

Keep tests independent and clear

Automated Solution

Postman

pm.test('Status code is 200', () => {
    pm.response.to.have.status(200);
});

const jsonData = pm.response.json();
pm.test('Response has userId', () => {
    pm.expect(jsonData).to.have.property('userId');
});
pm.test('Response has id', () => {
    pm.expect(jsonData).to.have.property('id');
});
pm.test('Response has title', () => {
    pm.expect(jsonData).to.have.property('title');
});
pm.test('Response has body', () => {
    pm.expect(jsonData).to.have.property('body');
});

This script is written in Postman test tab using pm API.

First, it checks if the response status code is 200, meaning the request was successful.

Then, it parses the response JSON and verifies that the expected fields userId, id, title, and body exist in the response.

Using environment variable {{baseUrl}} in the request URL allows easy switching of target servers without changing the test code.

Common Mistakes - 3 Pitfalls

Hardcoding the full URL instead of using environment variables

Not checking the response status code before validating response body

Using incorrect syntax for pm.expect assertions

Bonus Challenge

Now add data-driven testing by running the same request with environment variables for post IDs 1, 2, and 3

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