Send request block in Postman - Build an Automation Script

Send a POST request with JSON body and verify response status

Preconditions (3)

Step 1: Open Postman and create a new POST request

Step 2: Enter the URL https://api.example.com/login in the request URL field

Step 3: Select POST method

Step 4: Go to the Body tab and select raw and JSON format

Step 5: Enter the JSON body: {"username": "testuser", "password": "Test@123"}

Step 6: Click the Send button

Step 7: Observe the response status code and body

✅ Expected Result: Response status code is 200 and response body contains a token field

Automation Requirements - Postman/Newman

Assertions Needed:

Verify response status code is 200

Verify response body contains a non-empty token field

Best Practices:

Use environment variables for URL and credentials

Use test scripts in Postman to assert response

Avoid hardcoding sensitive data in the request body

Use descriptive names for requests and collections

Automated Solution

Postman

pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});
pm.test('Response has token', function () {
    var jsonData = pm.response.json();
    pm.expect(jsonData.token).to.exist;
    pm.expect(jsonData.token).to.be.a('string').that.is.not.empty;
});

The first test checks if the response status code is exactly 200, which means the request was successful.

The second test parses the JSON response body and verifies that the token field exists, is a string, and is not empty. This confirms that the login was successful and a token was returned.

Using pm.test allows grouping assertions with clear descriptions. Parsing JSON with pm.response.json() is the standard way to access response data in Postman scripts.

Common Mistakes - 3 Pitfalls

Hardcoding the API URL and credentials directly in the request body

Not checking the response status code before accessing response body

Using incorrect assertion syntax like pm.expect(response.status).toBe(200)

Bonus Challenge

Now add data-driven testing with 3 different sets of user credentials to verify login success or failure.

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