Response body array assertions in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ assertion

intermediate

Check if response array contains an object with a specific property value

Given a JSON response body containing an array of user objects, which Postman test script correctly asserts that at least one user has the username 'alice'?

Postman

pm.test('Response has user with username alice', () => {
    const jsonData = pm.response.json();
    // Write assertion here
});

A pm.expect(jsonData.includes('alice')).to.be.true;

B pm.expect(jsonData.some(user => user.username === 'alice')).to.be.true;

C pm.expect(jsonData.filter(user => user.username === 'alice')).to.have.lengthOf(0);

D pm.expect(jsonData.find(user => user.username === 'alice')).to.equal(true);

💡 Hint

Use an array method that returns true if any element matches the condition.

Option B uses the 'some' method to check if any user object has username 'alice', then asserts it is true. Option B incorrectly compares an object to true. Option B checks for zero matches, which is opposite of the goal. Option B tries to check if the array includes a string directly, which won't work for objects.

❓ assertion

intermediate

Assert the length of an array in response body

How do you write a Postman test to assert that the response body array has exactly 5 items?

Postman

pm.test('Response array length is 5', () => {
    const jsonData = pm.response.json();
    // Write assertion here
});

A pm.expect(jsonData.length).to.equal(5);

B pm.expect(jsonData).to.have.length(5);

C pm.expect(jsonData.size).to.equal(5);

D pm.expect(jsonData.count).to.equal(5);

💡 Hint

Use the correct property to get array length in JavaScript.

Option A correctly uses 'length' property to check array size. Option A uses 'length' as a method which is invalid. Options C and D use non-existent properties 'size' and 'count'.

❓ Predict Output

advanced

What is the result of this Postman test script?

Consider the following response body and test script. What will be the test result (pass or fail)?

Postman

/* Response body JSON */
[
  {"id": 1, "active": true},
  {"id": 2, "active": false},
  {"id": 3, "active": true}
]

/* Test script */
pm.test('All users are active', () => {
    const jsonData = pm.response.json();
    pm.expect(jsonData.every(user => user.active)).to.be.true;
});

A Fail - response is not an array

B SyntaxError - incorrect use of every method

C Pass - all users have active true

D Fail - not all users have active true

💡 Hint

Check if every user object has active set to true.

The response array has one user with active false (id 2), so 'every' returns false and the assertion fails.

❓ locator

advanced

Choose the correct JSON path to select all 'name' fields in an array response

Given a response body array of objects with a 'name' property, which JSON path expression correctly selects all 'name' values?

A $[*].name

B $.name

C $.name[*]

D $[*].['name']

💡 Hint

Use the wildcard to select all elements in the array, then access the 'name' property.

Option A correctly uses '$[*].name' to select the 'name' property from each element in the root array. Option A is invalid syntax. Option A selects 'name' from root object, not array elements. Option A has incorrect bracket usage.

❓ framework

expert

Identify the correct Postman test script to assert sorted order of array by 'score'

You receive a response body array of objects with a numeric 'score' property. Which Postman test script correctly asserts that the array is sorted in ascending order by 'score'?

Postman

pm.test('Array is sorted by score ascending', () => {
    const jsonData = pm.response.json();
    // Write assertion here
});

A pm.expect(jsonData.map(v => v.score).sort()).to.eql(jsonData.map(v => v.score));

B pm.expect(jsonData.reduce((acc,v) => acc && v.score >= acc.score, jsonData[0])).to.be.true;

C pm.expect(jsonData.every((v,i,a) => i === 0 || a[i-1].score <= v.score)).to.be.true;

D pm.expect(jsonData.sort((a,b) => a.score - b.score)).to.eql(jsonData);

💡 Hint

Check each element compared to the previous one to confirm ascending order.

Option C uses 'every' to check each element's score is greater or equal to the previous, correctly asserting ascending order. Option C misuses reduce and will cause a runtime error. Option C sorts the array in place, changing it, so the comparison fails. Option C sorts scores as strings, causing incorrect comparison.