Generating dynamic data in Postman - Build an Automation Script

Generate dynamic user data for API request

Preconditions (2)

Step 1: Open Postman and create a new POST request to https://api.example.com/users

Step 2: In the Body tab, select raw and JSON format

Step 3: Add JSON body with fields: name, email, and phone

Step 4: Use Postman dynamic variables to generate random name, email, and phone

Step 5: Send the request

Step 6: Verify the response status is 201 Created

Step 7: Verify the response body contains the same name and email as sent

✅ Expected Result: The API accepts the dynamically generated user data and returns status 201 with the correct user details in the response body

Automation Requirements - Postman Tests (JavaScript)

Assertions Needed:

Response status code is 201

Response body contains the sent name

Response body contains the sent email

Best Practices:

Use Postman dynamic variables like {{$randomFirstName}}, {{$randomEmail}}

Write assertions in the Tests tab using pm.expect

Keep test scripts clear and maintainable

Automated Solution

Postman

pm.test('Status code is 201', function () {
    pm.response.to.have.status(201);
});

const responseJson = pm.response.json();

pm.test('Response contains sent name', function () {
    pm.expect(responseJson.name).to.eql(pm.variables.get('name'));
});

pm.test('Response contains sent email', function () {
    pm.expect(responseJson.email).to.eql(pm.variables.get('email'));
});

This test script runs after the request is sent.

First, it checks the response status is 201, meaning the user was created successfully.

Then it parses the JSON response body.

It asserts that the response's name and email fields match the values sent in the request, which are stored in Postman variables.

This ensures the API accepted the dynamic data correctly.

Common Mistakes - 3 Pitfalls

Hardcoding user data instead of using dynamic variables

Not storing dynamic data in variables for assertions

Using incorrect assertion syntax in Postman tests

Bonus Challenge

Now add data-driven testing by running the request with 3 different sets of dynamic user data automatically

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