Header assertions in Postman - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a header assertion in API testing?

A header assertion checks if the response headers from an API contain expected values, like content type or authorization status.

beginner

How do you assert a response header in Postman?

Use the test script with pm.response.headers.get('Header-Name') and compare it to the expected value using assertions.

beginner

Why is it important to check the 'Content-Type' header in API responses?

Because it tells the client how to interpret the response data, like JSON or HTML, ensuring correct processing.

intermediate

Example of a Postman test script to check if 'Content-Type' is 'application/json'.

pm.test('Content-Type is application/json', () => { pm.response.to.have.header('Content-Type'); pm.expect(pm.response.headers.get('Content-Type')).to.include('application/json'); });

beginner

What happens if a header assertion fails in Postman?

The test will fail and show an error in the test results, indicating the header did not match the expected value.

Which Postman method retrieves a response header value?

A pm.response.header('Header-Name')

B pm.request.headers.get('Header-Name')

C pm.response.body.get('Header-Name')

D pm.response.headers.get('Header-Name')

pm.response.headers.get('Header-Name') correctly fetches the value of a response header.

What does the 'Content-Type' header specify in an API response?

A The size of the response body

B The format of the response data

C The server's IP address

D The HTTP status code

The 'Content-Type' header tells the client the format of the response data, like JSON or XML.

If a header assertion fails in Postman, what is the result?

A The test fails and shows an error

B The response body is ignored

C The request is retried automatically

D The test passes silently

A failed header assertion causes the test to fail and displays an error in the test results.

Which of these is a valid assertion to check a header exists in Postman?

A pm.response.header.exists('Authorization')

B pm.response.has.header('Authorization')

C pm.response.to.have.header('Authorization')

D pm.response.check.header('Authorization')

pm.response.to.have.header('Authorization') is the correct syntax to assert header presence.

Why should you test headers in API responses?

A To verify response data format and security info

B To check the server's uptime

C To measure response time

D To validate the request payload

Headers contain important info like data format and security details, so testing them ensures correct API behavior.

Explain how to write a Postman test to assert that the 'Content-Type' header is 'application/json'.

Think about checking header presence first, then comparing its value.

Why are header assertions important in API testing? Give two reasons.

Consider what headers tell the client about the response.