Response headers in Postman - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get the value of the 'Content-Type' header from the response.

Postman

let contentType = pm.response.headers.get('[1]');

Drag options to blanks, or click blank then click option'

AContent-Length

BContent-Type

CDate

DServer

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Content-Length' instead of 'Content-Type'.

Misspelling the header name or missing the hyphen.

The 'Content-Type' header tells us the media type of the response. Using pm.response.headers.get('Content-Type') retrieves its value.

2fill in blank

medium

Complete the code to check if the response headers include 'Cache-Control'.

Postman

let hasCacheControl = pm.response.headers.has('[1]');

Drag options to blanks, or click blank then click option'

AETag

BExpires

CCache-Control

DLast-Modified

Attempts:

3 left

💡 Hint

Common Mistakes

Checking for 'Expires' instead of 'Cache-Control'.

Using lowercase or misspelled header names.

The has() method checks if a header exists. We want to check for 'Cache-Control' exactly.

3fill in blank

hard

Fix the error in the code to correctly assert the 'Server' header value is 'nginx'.

Postman

pm.test('Server header is nginx', function () {
    pm.expect(pm.response.headers.get('[1]')).to.eql('nginx');
});

Drag options to blanks, or click blank then click option'

AServer

Bserver

CSERVER

Dservers

Attempts:

3 left

💡 Hint

Common Mistakes

Using lowercase 'server' which may not match the header name.

Using plural 'servers' which is incorrect.

Header names are case-insensitive but Postman expects the exact header name as sent. 'Server' is the correct header name to get.

4fill in blank

hard

Fill both blanks to create a test that asserts the 'Content-Length' header is greater than 100.

Postman

pm.test('Content-Length is greater than 100', function () {
    pm.expect(parseInt(pm.response.headers.get('[1]'))).to.be.[2](100);
});

Drag options to blanks, or click blank then click option'

AContent-Length

Babove

Cbelow

Dequal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'below' or 'equal' instead of 'above' for the assertion.

Not parsing the header value to an integer before comparing.

We get the 'Content-Length' header and parse it as an integer. Then we assert it is above 100 using to.be.above(100).

5fill in blank

hard

Fill all three blanks to create a test that asserts the 'ETag' header exists and starts with a double quote.

Postman

pm.test('ETag header exists and starts with a quote', function () {
    let etag = pm.response.headers.get('[1]');
    pm.expect(etag).to.not.be.[2];
    pm.expect(etag.startsWith('[3]')).to.be.true;
});

Drag options to blanks, or click blank then click option'

AETag

Bnull

C"

Dundefined

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'undefined' instead of 'null' in the assertion.

Forgetting to check the header exists before calling startsWith.

We get the 'ETag' header, assert it is not null, and check it starts with a double quote character.

Practice

1. What does the pm.response.headers.get('Content-Type') command do in Postman tests?

easy

A. It lists all headers in the response.

B. It sets the 'Content-Type' header in the request.

C. It deletes the 'Content-Type' header from the response.

D. It retrieves the value of the 'Content-Type' header from the response.

Solution

1. Step 1: Understand the method purpose

   The method pm.response.headers.get() is used to read a specific header from the response.

2. Step 2: Apply to 'Content-Type' header

   Using 'Content-Type' as the argument returns the value of that header from the server's reply.

3. Final Answer:

   It retrieves the value of the 'Content-Type' header from the response. -> Option D

4. Quick Check:

   pm.response.headers.get('Content-Type') = header value [OK]

Hint: Get header value with pm.response.headers.get('Header-Name') [OK]

Common Mistakes:

• Confusing get() with setting headers
• Thinking it deletes headers
• Assuming it returns all headers

2. Which of the following is the correct syntax to check if the response header 'Cache-Control' equals 'no-cache' in a Postman test script?

easy

A. pm.response.headers.get('Cache-Control') === 'no-cache';

B. pm.response.headers['Cache-Control'] == 'no-cache';

C. pm.response.headers.get('Cache-Control') = 'no-cache';

D. pm.response.headers.has('Cache-Control', 'no-cache');

Solution

1. Step 1: Identify correct method to get header value

   The method to get a header value is pm.response.headers.get('Header-Name').

2. Step 2: Use strict equality to compare value

   To check if the header equals 'no-cache', use === 'no-cache' for exact match.

3. Final Answer:

   pm.response.headers.get('Cache-Control') === 'no-cache'; -> Option A

4. Quick Check:

   Use get() + === for header value check [OK]

Hint: Use get() and === to compare header values correctly [OK]

Common Mistakes:

• Using single = instead of === for comparison
• Trying to access headers like an object property
• Using non-existent has() method with two arguments

3. Given this Postman test code:

const server = pm.response.headers.get('Server');
pm.test('Server header is Apache', () => {
  pm.expect(server).to.equal('Apache');
});

What will happen if the response header 'Server' is actually 'nginx'?

medium

A. The test will fail because the header value is not 'Apache'.

B. The test will be skipped automatically.

C. The test will throw a syntax error.

D. The test will pass because the header exists.

Solution

1. Step 1: Understand the test expectation

   The test expects the 'Server' header value to be exactly 'Apache'.

2. Step 2: Compare actual header value

   If the actual header is 'nginx', the expectation pm.expect(server).to.equal('Apache') will fail.

3. Final Answer:

   The test will fail because the header value is not 'Apache'. -> Option A

4. Quick Check:

   Expected 'Apache', got 'nginx' = fail [OK]

Hint: Test fails if header value differs from expected string [OK]

Common Mistakes:

• Assuming test passes if header exists
• Confusing syntax error with assertion failure
• Thinking test skips on mismatch

4. You wrote this Postman test to check the 'Content-Length' header:

pm.test('Content-Length is 1234', () => {
  pm.expect(pm.response.headers.get('Content-Length')).to.equal(1234);
});

But the test always fails even when the header shows '1234'. What is the likely problem?

medium

A. pm.response.headers.get() cannot read 'Content-Length'.

B. The header name is case-sensitive and should be lowercase.

C. The header value is a string, but test compares to a number.

D. The test syntax is invalid and causes an error.

Solution

1. Step 1: Check data types in comparison

   The header value returned by pm.response.headers.get() is always a string.

2. Step 2: Identify mismatch in expected value type

   The test compares the string '1234' to the number 1234, causing the equality check to fail.

3. Final Answer:

   The header value is a string, but test compares to a number. -> Option C

4. Quick Check:

   Compare string to string to pass test [OK]

Hint: Compare header values as strings, not numbers [OK]

Common Mistakes:

• Comparing string header to number directly
• Assuming header names are case-sensitive
• Believing get() cannot read standard headers

5. You want to write a Postman test that fails if the response does NOT include the header X-Security or if its value is not enabled. Which code snippet correctly implements this?

hard

A. pm.test('X-Security header check', () => {
const header = pm.response.headers.get('X-Security');
pm.expect(header || 'enabled').to.equal('enabled');
});

B. pm.test('X-Security header check', () => {
pm.expect(pm.response.headers.has('X-Security')).to.be.true;
pm.expect(pm.response.headers.get('X-Security')).to.equal('enabled');
});

C. pm.test('X-Security header check', () => {
pm.expect(pm.response.headers.get('X-Security')).to.be.true;
pm.expect(pm.response.headers.get('X-Security')).to.equal('enabled');
});

D. pm.test('X-Security header check', () => {
pm.expect(pm.response.headers.has('X-Security', 'enabled')).to.be.true;
});

Solution

1. Step 1: Check header existence explicitly

   Use pm.response.headers.has('X-Security') to confirm the header is present.

2. Step 2: Verify header value equals 'enabled'

   Use pm.response.headers.get('X-Security') and compare with 'enabled' using to.equal().

3. Step 3: Combine both checks in one test

   Both conditions must be true for the test to pass, ensuring header presence and correct value.

4. Final Answer:

   Use has() to check presence and get() to check value. -> Option B

5. Quick Check:

   has() + get() ensures header exists and matches value [OK]

Hint: Use has() to check header exists before checking value [OK]

Common Mistakes:

• Not checking header existence before value
• Using get() without verifying header presence
• Assuming get() returns undefined if header missing