30 Postman Interview Questions Answers

Title: 30 Postman Interview Questions and Answers: Ace Your Next API Testing Interview

Postman, the popular API client, has become an indispensable tool for developers, testers, and API enthusiasts. As the demand for robust and efficient APIs continues to rise, proficiency in Postman is a sought-after skill in the software industry. Whether you’re a fresher or an experienced professional, preparing for a Postman interview can be a daunting task. In this article, we’ll explore 30 essential Postman interview questions and answers to help you ace your next API testing interview.

What is Postman?

Postman is a powerful collaboration platform for API development. It is an API client that allows you to design, build, share, test, and document APIs seamlessly. Postman simplifies the process of sending HTTP/HTTPS requests to a service and analyzing the responses, ensuring that the service is up and running as expected.

Why Use Postman?

There are several compelling reasons to use Postman for API testing:

1. Free and Easy to Use: Postman is available as a free download and can be used by teams of any size. It has a user-friendly interface, allowing you to send your first request within minutes.

2. API Support: Postman supports various types of API calls, including REST, SOAP, and plain HTTP, enabling you to inspect even the largest responses with ease.

3. Extensibility: Postman can be customized to suit your needs with its powerful API.

4. Collaboration and Integration: Postman facilitates team collaboration by allowing you to share collections, requests, and test suites. It can also be easily integrated into your preferred CI/CD service with Newman (a command-line collection runner).

5. Excellent Community and Support: Postman has a vast community forum where you can find solutions to any technical issues you may encounter while using the tool.

Postman Interview Questions and Answers

Basic Postman Concepts

1. What is an API?
   API stands for Application Programming Interface. It is a set of rules, protocols, and tools for building software applications. APIs specify how one software program should interact with another software program, acting as an interface between the two applications.

2. Name some tools used for API testing.
   Some popular tools used for API testing include Postman, SoapUI, Katalon Studio, Tricentis Tosca, Apigee, and JMeter.

3. What are the core components of an HTTP request?
   An HTTP request consists of five key components:

   • HTTP methods (GET, PUT, POST, DELETE)
   • Uniform Resource Identifier (URI)
   • HTTP version (e.g., HTTP v1.1)
   • Request headers (e.g., Content-Type, Content-Length)
   • Request body or payload

4. State the core components of an HTTP response.
   An HTTP response typically includes four key components:

   • Status/response code (e.g., 200 OK, 404 Not Found)
   • HTTP version
   • Response headers (e.g., Content-Type, Content-Length, Date)
   • Response body

5. What API information is exposed in web developer tools?
   Web developer tools expose information about request headers, response body, and response cookies.

6. What can we use to get API information from web developer tools into Postman?
   You can use the “Copy as cURL” option to get API information from web developer tools into Postman.

Postman Basics

1. How do you create and send a request in Postman?
   To create and send a request in Postman, follow these steps:

   • Open Postman and create a new request by selecting the appropriate HTTP method (GET, POST, PUT, DELETE) from the dropdown menu.
   • Enter the request URL in the address bar.
   • Add any required headers, query parameters, or request body data.
   • Click the “Send” button to send the request to the API server.

2. What are some key features of Postman that you find most useful in your testing workflow?
   Some key features of Postman that are often found useful in testing workflows include:

   • Collections for organizing and grouping related requests
   • Variables and environments for parameterizing requests and managing different testing environments
   • Test scripts for automating assertions and validations
   • Pre-request scripts for performing actions before sending a request
   • Request history for revisiting and retesting previous requests
   • Collection Runner for executing multiple requests as a test suite

3. How do you handle authentication and authorization in Postman?
   Postman provides multiple ways to handle authentication and authorization, including:

   • Basic Authentication: Including the username and password in the request headers
   • Token-based Authentication: Including tokens (e.g., JWT, OAuth) in the request headers or query parameters
   • API Key: Passing an API key as a request header or query parameter
   • OAuth 2.0: Built-in support for various OAuth flows, such as Authorization Code or Client Credentials
   • Custom Authentication: Implementing custom authentication mechanisms using Postman’s scripting capabilities

4. Can you describe the process of creating and running automated tests in Postman?
   To create and run automated tests in Postman, follow these steps:

   • Create a new request or open an existing one.
   • Write test scripts using JavaScript to validate the API response, assert specific conditions, or extract data.
   • Save the request in a collection.
   • Open the collection, and write test scripts for individual requests or the entire collection.
   • Run the collection, and Postman will execute the tests, highlighting any failures or errors.

Intermediate Postman Concepts

1. What is a collection in Postman?
   A collection in Postman allows you to group related requests together. It helps you organize your requests into folders systematically.

2. What is meant by the term “environment” in Postman?
   An environment in Postman is a set of key-value pairs. You can create multiple environments and switch between them quickly with a button press. There are two types of environments: global and local, defining the variable’s scope.

3. What is the purpose of the Postman monitor?
   The Postman monitor is used for running collections. Collections are run until a specified time defined by the user. Postman Monitor requires the user to be logged in, and monitor reports are shared via email on a daily or monthly basis.

4. What do you understand by the term “Postman Collection runners”?
   A Postman collection runner is used to perform data-driven testing. A group of API requests is run in a collection for multiple iterations with different sets of data.

5. What is Postman cloud, and why is it not preferred to save work there?
   The Postman cloud is a common repository where companies can access Postman collections. It allows you to instantly save work after logging in, and team members can access data and collections from anywhere. However, it is not recommended to save company work in the Postman cloud due to potential security breaches and the confidential nature of the work.

6. What is the purpose of the 304 status code?
   The 304 status code means “Not Modified.” It is used to reduce network bandwidth usage in conditional GET requests. The response body should be empty, and the headers should include information like dates and locations.

7. Define the 201 status code.
   The 201 status code indicates that a resource has been created successfully using a POST or PUT request. It returns a link to the newly created resource using the location header.

8. When do we use global variables, collection variables, and local variables?

   • Global variables are general-purpose variables ideal for quick results and prototyping. They are used for passing data to other requests.
   • Collection variables are typically used for storing constants that do not change during the execution of the collection, as well as for URLs and authentication credentials when only one environment exists.
   • Local variables are only available within the request that set them or when using Newman/Collection Runner during the entire execution. They are used whenever you want to override all other variable scopes.

9. How do you remove local variables?
   Local variables are automatically removed once the tests have been executed.

10. What is the difference between form data and x-www-form-urlencoded?
    The primary difference between form data and x-www-form-urlencoded is that the URL is encoded when sent through x-www-form-urlencoded.

Advanced Postman Concepts

1. How do you access the history of requests in Postman?
   You can access the history of requests in Postman through the “History” tab. The request history is synced across all your logged-in devices when you log in to your Postman account.

2. Why is Base64 encoding primarily used in Postman?
   Base64 encoding is primarily used in Postman because the data is transmitted in textual form and sent in a more accessible format, like HTML form data. Base64 is popular because we can rely on the same 64 characters regardless of the encoding language used.

3. What are the various variable scopes provided by Postman?
   Postman provides the following variable scopes:

   • Global variables
   • Local variables
   • Environment variables
   • Collection variables
   • Data variables

4. Is it possible to reuse the authentication token for multiple requests?
   Yes, it is possible to reuse the authentication token for multiple requests. To achieve this, you can create a collection, add all requests with the same authentication token, and assign the collection with the auth token. You can then apply it to each request separately by choosing “Inherit auth from parent” under the “Authorization” tab.

5. How do you write test cases for basic authentication in Postman?
   To write test cases for basic authentication in Postman, follow these steps:

   • Configure the API’s credentials by going to the “Authorization” tab, choosing “Basic Auth” from the dropdown, and entering the username and password.
   • Write test cases like this:
     javascript

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     pm.test("Is the Request Authenticated?", function () {  var jsonData = pm.response.json();  pm.expect(jsonData.authenticated).to.eql(true);});pm.test("Is the Content-Type present?", function () {  pm.response.to.have.header("Content-Type");});pm.test("Is it a successful POST Request?", function () {  pm.response.to.have.status(200);});

6. How do you set the same headers for all requests in a Postman Collection?
   To set the same headers for all requests in a Postman Collection, follow these steps:

   • Right-click the collection and access the “Pre-request” tab.
   • Add the following code to add a request header for each request in the collection:
     javascript

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     pm.request.headers.add({  key: 'TestHeader',  value: 'testValue'});

   • Click “Update” to save the script.
   • Run the requests in the collection and check the Postman console to ensure the headers have been added.

7. What are workspaces in Postman, and what are their uses?
   Postman workspaces are spaces where one or more people can collaborate on the same collections or sets of collections. They allow logical separation of collections or requests. Postman supports two types of workspaces: Team and Personal.

8. Does Postman provide a feature to log requests and responses?
   Yes, Postman provides a feature called “Postman Console” to log requests and responses. By including console.log statements in your scripts, you can log additional information in the console, enabling you to inspect every request and response detail.

9. How do you stop the execution of upcoming requests or the execution of collections?
   You can use the code pm.setNextRequest(null) to stop processing the next request or the execution of collections.

10. How do you generate random numbers within a given range in Postman?
    To generate random numbers within a given range in Postman, you can use the following pre-request script:

    javascript

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    pm.globals.set('randomNumber', Math.floor(Math.random() * N));

    You can then use the variable {{randomNumber}} in the URL.

By mastering these Postman interview questions and answers, you’ll be well-prepared to showcase your proficiency in API testing and development using Postman. Remember, practice is key, so continually hone your skills by working on real-world projects and staying up-to-date with the latest Postman features and best practices.