Test utilities and helpers in Postman - Build an Automation Script

Verify custom test utility function for response validation

Preconditions (2)

Step 1: Create a new Postman request with GET method to https://api.example.com/users

Step 2: Write a test utility function in the Tests tab that checks if the response status is 200

Step 3: Write a helper function that verifies the response body contains a 'users' array

Step 4: Call these utility and helper functions inside the Tests tab

Step 5: Send the request

Step 6: Observe the test results in the Postman Test Results tab

✅ Expected Result: The test results show that the status code is 200 and the response body contains a 'users' array

Automation Requirements - Postman Tests (JavaScript)

Assertions Needed:

Verify response status code is 200

Verify response body has a 'users' array

Best Practices:

Use reusable functions for common checks

Use pm.expect assertions for clear test results

Keep test code clean and readable

Automated Solution

Postman

function checkStatus200() {
    pm.test('Status code is 200', function () {
        pm.response.to.have.status(200);
    });
}

function checkUsersArray() {
    pm.test('Response has users array', function () {
        const jsonData = pm.response.json();
        pm.expect(jsonData).to.have.property('users').that.is.an('array');
    });
}

// Call utility functions
checkStatus200();
checkUsersArray();

The checkStatus200 function creates a test to verify the response status code is 200 using pm.response.to.have.status(200). This confirms the request succeeded.

The checkUsersArray function parses the JSON response and asserts that it has a property users which is an array. This checks the expected data structure.

Both functions are called in the Tests tab to keep the test code organized and reusable. Using pm.test and pm.expect provides clear pass/fail results in Postman.

Common Mistakes - 3 Pitfalls

Writing all assertions directly without reusable functions

Not parsing response JSON before accessing properties

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

Bonus Challenge

Extend the test utilities to check that each user object in the 'users' array has 'id' and 'name' properties

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