Using Chai assertion library in Postman - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to assert that the response status is 200.

Postman

pm.test('Status code is 200', function () {
    pm.response.to.have.status([1]);
});

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

A200

B404

C500

D201

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong status code like 404 or 500.

Forgetting to put the status code as a number.

The correct status code for a successful HTTP response is 200. Using pm.response.to.have.status(200) asserts this.

2fill in blank

medium

Complete the code to assert that the response body contains the string 'success'.

Postman

pm.test('Body contains success', function () {
    pm.expect(pm.response.text()).to.include([1]);
});

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

A'fail'

B'error'

C'success'

D'warning'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a word that does not appear in the response.

Not using quotes around the string.

The assertion checks if the response text includes the word 'success'. This confirms the expected message is present.

3fill in blank

hard

Fix the error in the assertion to check that the JSON response has a property 'id'.

Postman

pm.test('Response has id property', function () {
    pm.expect(pm.response.json()).to.have.[1]('id');
});

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

Alength

Bstatus

Cinclude

Dproperty

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'length' which checks array size, not property existence.

Using 'status' which is unrelated here.

The correct Chai assertion to check for a property in an object is to.have.property('id').

4fill in blank

hard

Fill both blanks to assert that the response JSON array length is greater than 0.

Postman

pm.test('Array length is positive', function () {
    pm.expect(pm.response.json().length).to.be.[1](0).[2](0);
});

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

AgreaterThan

Babove

Cbelow

Dequal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'below' or 'equal' which check wrong conditions.

Mixing the order of chaining words.

Chai uses to.be.above(0) or to.be.greaterThan(0) to check if a number is greater than zero. Here, above and greaterThan are chained.

5fill in blank

hard

Fill all three blanks to assert that the response JSON object's 'name' property equals 'John'.

Postman

pm.test('Name is John', function () {
    pm.expect(pm.response.json().[1]).[2].[3]('John');
});

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

Aname

Bequal

Cto

Dstatus

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong property name.

Mixing the order of chaining words.

Using 'status' instead of 'equal'.

The correct assertion accesses the 'name' property, then uses to.equal('John') to check its value.

Practice

1. What is the main purpose of using the Chai assertion library in Postman tests?

easy

A. To create user interface elements

B. To write clear and readable checks for API responses

C. To send HTTP requests faster

D. To store environment variables

Solution

1. Step 1: Understand Chai's role in testing

   Chai is used to write assertions that check if API responses meet expectations.

2. Step 2: Identify the correct purpose in Postman context

   In Postman, Chai helps create readable tests that verify API behavior.

3. Final Answer:

   To write clear and readable checks for API responses -> Option B

4. Quick Check:

   Chai assertions = readable API checks [OK]

Hint: Chai is for checking API results clearly [OK]

Common Mistakes:

• Confusing Chai with request sending
• Thinking Chai creates UI elements
• Mixing Chai with environment variable storage

2. Which of the following is the correct syntax to assert that the response status code is 200 using Chai in Postman?

easy

A. pm.expect(response.code).to.equal(200);

B. pm.expect(pm.response.status).to.equal(200);

C. pm.expect(pm.response.code).to.equal(200);

D. pm.expect(response.status).to.be(200);

Solution

1. Step 1: Identify the correct Postman response object

   The response object in Postman is accessed via pm.response.

2. Step 2: Use Chai syntax to check status code

   The correct Chai assertion is pm.expect(pm.response.code).to.equal(200);.

3. Final Answer:

   pm.expect(pm.response.code).to.equal(200); -> Option C

4. Quick Check:

   Status code check uses pm.response.code [OK]

Hint: Use pm.response.code with to.equal for status [OK]

Common Mistakes:

• Using wrong object like response.code
• Using to.be instead of to.equal
• Missing pm.response prefix

3. Given this Postman test code:

pm.test('Check response body', () => {
  pm.expect(pm.response.text()).to.include('success');
});

What will happen if the response body is 'Operation was successful'?

medium

A. Test will pass only if response code is 200

B. Test will fail because 'success' is not exactly matched

C. Test will throw a syntax error

D. Test will pass because 'success' is included in the response

Solution

1. Step 1: Understand the assertion used

   The assertion checks if the response text includes the substring 'success'.

2. Step 2: Check if 'success' is in 'Operation was successful'

   The word 'successful' contains 'success' as a substring, so the assertion passes.

3. Final Answer:

   Test will pass because 'success' is included in the response -> Option D

4. Quick Check:

   Substring check includes 'success' [OK]

Hint: Include checks pass if substring exists anywhere [OK]

Common Mistakes:

• Expecting exact match instead of substring
• Confusing syntax error with assertion failure
• Assuming status code affects this test

4. Identify the error in this Postman test code snippet:

pm.test('Status is 404', () => {
  pm.expect(pm.response.status).to.equal(404);
});

medium

A. pm.response.status is not the correct property for status code

B. to.equal should be to.be.equal

C. pm.test should be pm.expect

D. Missing semicolon after pm.test

Solution

1. Step 1: Check the property used for status code

   The correct property for status code in Postman is pm.response.code, not pm.response.status.

2. Step 2: Confirm Chai syntax correctness

   The to.equal syntax is correct and pm.test is used properly.

3. Final Answer:

   pm.response.status is not the correct property for status code -> Option A

4. Quick Check:

   Status code property is pm.response.code [OK]

Hint: Use pm.response.code for status, not pm.response.status [OK]

Common Mistakes:

• Using pm.response.status instead of pm.response.code
• Adding unnecessary 'to.be' in assertion
• Confusing pm.test with pm.expect

5. You want to write a Postman test that asserts the JSON response has a property userId with a value greater than 100. Which code snippet correctly uses Chai assertions to do this?

hard

A. pm.test('userId > 100', () => {
const jsonData = pm.response.json();
pm.expect(jsonData.userId).to.be.above(100);
});

B. pm.test('userId > 100', () => {
const jsonData = pm.response.json();
pm.expect(jsonData.userId).to.equal(100);
});

C. pm.test('userId > 100', () => {
pm.expect(pm.response.text()).to.include('userId > 100');
});

D. pm.test('userId > 100', () => {
pm.expect(pm.response.code).to.be.above(100);
});

Solution

1. Step 1: Parse JSON response correctly

   Use pm.response.json() to get the response as an object.

2. Step 2: Use Chai's 'above' assertion on userId property

   Check that jsonData.userId is greater than 100 with to.be.above(100).

3. Final Answer:

   pm.test('userId > 100', () => { const jsonData = pm.response.json(); pm.expect(jsonData.userId).to.be.above(100); }); -> Option A

4. Quick Check:

   Parse JSON then assert property above value [OK]

Hint: Parse JSON then use to.be.above for numeric checks [OK]

Common Mistakes:

• Using to.equal instead of to.be.above
• Checking response text instead of JSON property
• Checking status code instead of userId