What APIs are and why testing them matters in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding API Testing Importance

Why is testing APIs important in software development?

A Because APIs handle data exchange and must work correctly to avoid errors

B Because APIs are the user interface and need to look good

C Because APIs slow down the application and need to be disabled

D Because APIs are only used for internal logging and do not affect users

💡 Hint

Think about what APIs do between different software parts.

APIs allow different software parts to communicate. Testing ensures data is exchanged correctly and the system works as expected.

❓ Predict Output

intermediate

API Response Status Code Check

What is the output status code when this Postman test script runs if the API returns success?

Postman

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

A Test passes if status code is 404

B Test fails if status code is 200

C Test passes if status code is 200

D Test fails if status code is 500

💡 Hint

Look at the status code the test expects.

The test checks if the response status code is 200. If yes, the test passes.

❓ assertion

advanced

Validating JSON Response Structure

Which Postman test assertion correctly checks that the JSON response has a key named 'userId'?

A pm.expect(pm.response.json()).to.have.property('userId');

B pm.response.to.have.jsonKey('userId');

C pm.expect(pm.response.body).to.include('userId');

D pm.response.json().hasKey('userId');

💡 Hint

Check the correct syntax for property assertion in Postman.

Option A uses the correct Postman syntax to assert that the JSON response contains the 'userId' property.

🔧 Debug

advanced

Identifying Error in Postman Test Script

What error will this Postman test script cause?

Postman

pm.test('Check user name', function() {
    let jsonData = pm.response.json();
    pm.expect(jsonData.name).to.eql('Alice');
});

A No error, test passes

B Test fails because name is not 'Alice'

C SyntaxError due to missing parentheses

D TypeError because pm.response.json is not a function

💡 Hint

Check how to correctly call the json method in Postman.

pm.response.json is a function (method) and must be called with parentheses: pm.response.json(). Without them, jsonData is the function reference itself, not the parsed JSON object. Thus, jsonData.name is 'json' (the function name), causing the test to fail.

❓ framework

expert

Choosing Best Practice for API Test Automation

Which approach is best for automating API tests to ensure reliability and maintainability?

A Test APIs only through the user interface without direct API calls

B Write all API tests as one large script without modularization

C Manually run API tests only when bugs are reported

D Use a testing framework with reusable test cases and environment variables

💡 Hint

Think about how to keep tests organized and easy to update.

Using a testing framework with reusable tests and environment variables helps keep API tests reliable, maintainable, and easy to run in different setups.