Status codes reading in Postman - Build an Automation Script

Verify HTTP status codes for API responses

Preconditions (2)

Step 1: Send a GET request to the API endpoint https://jsonplaceholder.typicode.com/posts/1

Step 2: Observe the HTTP status code in the response

Step 3: Send a GET request to the API endpoint https://jsonplaceholder.typicode.com/posts/invalid

Step 4: Observe the HTTP status code in the response

✅ Expected Result: The first request returns status code 200 OK, the second request returns status code 404 Not Found

Automation Requirements - Postman Tests

Assertions Needed:

Verify response status code is 200 for valid request

Verify response status code is 404 for invalid request

Best Practices:

Use pm.response.to.have.status() for status code assertions

Write clear and descriptive test names

Keep tests independent and repeatable

Automated Solution

Postman

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

pm.sendRequest('https://jsonplaceholder.typicode.com/posts/invalid', (err, res) => {
    pm.test('Status code is 404 for invalid post', () => {
        pm.expect(res).to.have.property('code', 404);
    });
});

The first test checks that the response status code for a valid GET request is 200, which means OK.

The second test sends a request to an invalid URL and verifies the status code is 404, meaning Not Found.

Using pm.response.to.have.status() and pm.expect() ensures clear and reliable assertions.

Tests are independent and use Postman's built-in test functions for clarity.

Common Mistakes - 3 Pitfalls

Using incorrect assertion syntax like pm.response.status == 200

Not handling asynchronous requests properly in pm.sendRequest

Hardcoding URLs without verifying they exist

Bonus Challenge

Now add data-driven testing with 3 different API endpoints and verify their status codes

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