REST API fundamentals review in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding HTTP Methods in REST APIs

Which HTTP method is typically used to update an existing resource partially in a REST API?

A PUT

B POST

C PATCH

D GET

💡 Hint

Think about the method that allows partial updates without replacing the entire resource.

PATCH is used for partial updates of a resource, while PUT replaces the entire resource. GET retrieves data, and POST creates new resources.

❓ Predict Output

intermediate

Response Status Code Interpretation

What is the expected HTTP status code returned by a REST API after successfully creating a new resource?

A 201 Created

B 200 OK

C 204 No Content

D 400 Bad Request

💡 Hint

It indicates that a new resource was successfully created.

201 Created is the standard status code for successful resource creation. 200 OK is general success, 204 No Content means success with no body, and 400 Bad Request indicates client error.

❓ assertion

advanced

Validating JSON Response Structure

You receive this JSON response from a REST API call:

{"userId": 123, "name": "Alice", "email": "[e-mail]"}

Which Postman test script assertion correctly verifies the presence of the email field?

A pm.test('Email field exists', () => { pm.response.to.have.jsonBody('email'); });

B pm.test('Email field exists', () => { pm.response.body.email !== null; });

C pm.test('Email field exists', () => { pm.response.json().email !== undefined; });

D pm.test('Email field exists', () => { pm.expect(pm.response.json()).to.have.property('email'); });

💡 Hint

Use Postman's pm.expect with to.have.property to check JSON keys.

Option D correctly uses pm.expect to assert the JSON response has the email property. Option D uses a non-existent method, B and D do not assert properly.

🔧 Debug

advanced

Identifying the Cause of a 401 Unauthorized Error

You send a GET request to a protected REST API endpoint using Postman but receive a 401 Unauthorized response. Which of the following is the most likely cause?

A Authentication credentials are missing or invalid.

B The server is down.

C The request body is missing required fields.

D The API endpoint URL is incorrect.

💡 Hint

401 status means the server refuses access due to authentication issues.

401 Unauthorized means the request lacks valid authentication credentials. Incorrect URL usually returns 404, missing body fields often cause 400, and server down causes no response or 5xx errors.

❓ framework

expert

Automating REST API Tests in Postman Collections

Which Postman feature allows you to run a series of API requests with tests automatically and generate a detailed report?

A Postman Monitor

B Postman Collection Runner

C Postman Runner

D Postman Console

💡 Hint

It runs multiple requests in sequence and shows test results.

Postman Collection Runner lets you run all requests in a collection with tests and view results. Postman Monitor schedules runs in the cloud, Runner and Collection Runner are often used interchangeably but Collection Runner is the correct term. Postman Console is for debugging.