Nested object assertions in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ assertion

intermediate

Check nested property value in JSON response

Given the following JSON response, which Postman test assertion correctly verifies that the user's city is 'New York'?

Postman

{
  "user": {
    "id": 123,
    "name": "Alice",
    "address": {
      "city": "New York",
      "zip": "10001"
    }
  }
}

A pm.test('City is New York', () => { pm.expect(pm.response.json().user.city).to.eql('New York'); });

B pm.test('City is New York', () => { pm.expect(pm.response.json().user.address.city).to.eql('New York'); });

C pm.test('City is New York', () => { pm.expect(pm.response.json().address.city).to.eql('New York'); });

D pm.test('City is New York', () => { pm.expect(pm.response.json().user.address.zip).to.eql('New York'); });

💡 Hint

Remember to follow the exact path to the nested property in the JSON structure.

The city property is nested inside user.address. Option B correctly accesses user.address.city. Options A and C miss the correct nesting, and D checks the zip code instead of city.

❓ assertion

intermediate

Verify array length inside nested object

You receive this JSON response. Which assertion correctly checks that the user has exactly 3 phone numbers?

Postman

{
  "user": {
    "phones": ["123-4567", "234-5678", "345-6789"]
  }
}

A pm.test('User has 3 phones', () => { pm.expect(pm.response.json().user.phones).to.have.lengthOf(3); });

B pm.test('User has 3 phones', () => { pm.expect(pm.response.json().phones.length).to.eql(3); });

C pm.test('User has 3 phones', () => { pm.expect(pm.response.json().user.phones.length).to.eql(3); });

D pm.test('User has 3 phones', () => { pm.expect(pm.response.json().user.phones).to.eql(3); });

💡 Hint

Use the correct Chai assertion to check array length.

Option A uses the proper Chai assertion 'to.have.lengthOf' on the array. Option A compares length property with eql(3) which works but is less idiomatic. Option A accesses wrong path. Option A compares array to number, which is invalid.

❓ Predict Output

advanced

Output of nested object assertion with missing property

What will be the result of this Postman test if the JSON response is missing the 'email' property inside 'user'?

Postman

pm.test('User email exists', () => {
  pm.expect(pm.response.json().user.email).to.exist;
});

A Test is skipped automatically

B Test passes because 'email' is optional

C Test throws a runtime error due to accessing undefined property

D Test fails with assertion error because 'email' is undefined

💡 Hint

Check how Chai's 'to.exist' behaves with undefined values.

'to.exist' assertion fails if the value is undefined or null. Accessing a missing property returns undefined, so the test fails with an assertion error. It does not throw a runtime error.

🔧 Debug

advanced

Identify error in nested object assertion code

This Postman test is intended to check if the user's first hobby is 'reading'. What is the error in the code?

Postman

pm.test('First hobby is reading', () => {
  pm.expect(pm.response.json().user.hobbies[0] === 'reading');
});

A Missing assertion method like 'to.eql' causes test to always pass

B Incorrect property path to hobbies array

C Using '===' inside pm.expect causes syntax error

D No error, test is correct

💡 Hint

pm.expect needs a matcher method to assert values.

pm.expect expects a value followed by a matcher like 'to.eql'. Writing pm.expect(condition) without a matcher does not assert anything and the test passes regardless of condition.

❓ framework

expert

Best practice for nested object assertions in Postman tests

Which approach is best to safely assert a deeply nested property 'user.profile.contact.email' exists and equals '[e-mail]' without causing runtime errors if intermediate properties are missing?

A pm.expect(pm.response.json().user.profile.contact.email).to.eql('[e-mail]');

B if(pm.response.json().user && pm.response.json().user.profile && pm.response.json().user.profile.contact) { pm.expect(pm.response.json().user.profile.contact.email).to.eql('[e-mail]'); }

C const email = _.get(pm.response.json(), 'user.profile.contact.email'); pm.expect(email).to.eql('[e-mail]');

D pm.expect(pm.response.json()?.user?.profile?.contact?.email).to.eql('[e-mail]');

💡 Hint

Consider safe access methods to avoid runtime errors in nested assertions.

Option C uses lodash's _.get method to safely access nested properties without runtime errors if any intermediate property is missing. Option C throws error if any property is missing. Option C uses optional chaining but Postman sandbox may not support it fully. Option C is verbose and repeats calls.