Basic authentication in Postman - Build an Automation Script

Verify API access with Basic Authentication

Preconditions (3)

Step 1: Open Postman and create a new GET request

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

Step 3: Go to the Authorization tab

Step 4: Select 'Basic Auth' from the Type dropdown

Step 5: Enter username 'user1' and password 'pass123'

Step 6: Click Send to submit the request

✅ Expected Result: The API responds with status code 200 and returns the expected data in JSON format

Automation Requirements - Postman test scripts

Assertions Needed:

Verify response status code is 200

Verify response body contains expected data fields

Best Practices:

Use environment variables for username and password

Use pm.response.to.have.status for status code assertion

Use pm.expect with JSON parsing for response body validation

Automated Solution

Postman

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

pm.test('Response has expected data', () => {
    const jsonData = pm.response.json();
    pm.expect(jsonData).to.have.property('data');
    pm.expect(jsonData.data).to.be.an('array');
});

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

The second test parses the response body as JSON and verifies it contains a property named 'data' which should be an array. This confirms the API returned the expected data structure.

Using pm.response.to.have.status and pm.expect are Postman's recommended ways to write assertions in test scripts.

Environment variables for username and password help keep credentials secure and reusable.

Common Mistakes - 3 Pitfalls

Hardcoding username and password directly in the request

Not verifying the response status code

Assuming response body is always JSON without parsing

Bonus Challenge

Now add data-driven testing with 3 different username and password combinations

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