Postman Tutorial - Learn to Use Postman Hands-On

Postman Tutorial – A Guide for Complete Beginners

Postman Tutorial A Guide for Complete Beginners

Postman is one of the most sought-after tools when it comes to API testing. Whether you’re new or experienced, this tutorial simplifies API testing using Postman. We’ll cover the basics, explore testing techniques, and showcase implementable skills in this blog.

Below is the full video on API Testing Workshop where she shared her insights on how to make the best out of this tool even as a beginner.

What is Postman?

postman logo

Postman is a platform to build, test, design, modify, and document APIs. It is a simple Graphic User Interface for sending and viewing HTTP requests and responses. The tool is simple to learn when given enough time.  

Postman serves as a bridge between developers and APIs, allowing you to create requests to APIs, inspect responses, and automate workflows with ease. With its user-friendly interface, you can set up test suites and monitor API performance effortlessly. Postman also streamlines collaboration by enabling teams to share and document APIs, making it a central hub for API development. Whether you’re a seasoned developer or just starting, Postman is your go-to companion for API testing and managing APIs with efficiency and precision.

Check this resource on getting started with Postman: https://learning.postman.com/docs/getting-started/overview/

The Building Blocks of Postman and Variables

building blocks of postman

When it comes to simplifying your API (application programming) development process, Postman is a true lifesaver. To help you make the most of this fantastic API testing tool, let’s dive into its fundamental building blocks. In this exploration, we’ll break down these essential blocks in simple terms, so you can harness Postman’s potential with ease.

Workspaces: Think of Workspaces as your digital project folders. They’re like dedicated workspaces where you can organize your API-related work. Whether you’re collaborating with a team or managing your projects solo, Workspaces are your go-to places to keep everything in order.

Collections: Collections are your recipe books for API requests. They help you group related requests together, making it easy to find and use them when needed. Just like a cookbook organizes recipes by categories, Collections keep your API requests neatly organized.

Requests: Requests are the heart of your API (application programming) interactions. They’re like specific orders you place at a restaurant. With Postman, you can create, send, and receive these requests effortlessly. Each request is a unique action you take to get the data or perform an operation you need.

Environments: Environments act as your versatile spice racks. They store variables and values that can be used across different requests. Just as you use common spices in various dishes to add flavor, Environments ensure consistency and flexibility in your API interactions.

In essence, Postman’s building blocks are your toolkit for organizing, executing, and optimizing your API-related tasks. Workspaces provide the space to collaborate, Collections organize your requests, Requests are the actions you take, and Environments add flexibility to your projects. With Postman, you’re all set to simplify API testing and development with confidence.

Variables in Postman

In the world of API testing, efficiency and flexibility are your best friends. Postman understands this need and equips you with a range of variables to make your API testing and development more powerful. These variables play a vital role in customizing your requests, managing data, and maintaining consistency. In this blog, we’ll explore the various types of Postman variables that you can leverage to supercharge your testing efforts.

variables in postman

1. Global Variables

Think of global variables as your Swiss Army knife in Postman. These variables are accessible throughout your entire Postman workspace. They are like constants you can rely on across collections, requests, and environments. Use global variables to store information that remains consistent across your API testing projects.

2. Collection Variables

Collection variables are specific to the collection they belong to. They act like notes you scribble in the margins of a particular recipe in your cookbook. In Postman, you can use collection variables to customize requests and tests within a specific collection, keeping things neatly organized.

3. Environment Variables

Environments are your dynamic workspace in Postman, and environment variables are its building blocks. These variables are scoped to a particular environment, ensuring that your data and configurations remain separate and easily manageable for different use cases. You can adjust these variables based on the environment you’re working in, whether it’s development, testing, or production.

4. Local Variables

Local variables are like post-it notes you stick on your computer screen to remember something while working on a specific task. In Postman, local variables are used within a single request or script. They’re handy for temporary data storage or calculations related to a particular request.

5. Data Variables

Data variables are all about versatility. They allow you to use data from external sources like CSV or JSON files within your requests. This enables you to perform data-driven testing, looping through different inputs, and validating responses with ease. Data variables are the perfect choice when you need to test your API with a variety of scenarios.

Exporting and Importing Collections

In the domain of API development, collaboration stands as a cornerstone. Postman, the versatile tool known for its prowess in streamlining API testing and development, fully recognizes the significance of collaborative efforts.

It empowers you with the ability to easily share your API collections with teammates and integrate them into various workflows. In this blog post, we’ll explore the invaluable process of exporting and importing collections in Postman.

Exporting Collections: Sharing the Wealth

Exporting a collection in Postman is akin to creating a copy of your carefully crafted API requests, tests, and documentation. This copy can then be shared with your team members, partners, or anyone else involved in your project. Here’s how to do it:

  • Open the Postman app and locate the collection you want to export in your workspace.
  • Right-click on the collection and select “Export.”
  • Choose your preferred export format. Postman allows you to export collections in various formats, including JSON, Postman Collection v1, and Postman Collection v2.
  • Select the location where you want to save the exported collection and click “Save.”

Once your collection is exported, you can share it with others via email, a cloud storage service, or by simply sending the exported file. The recipient can then import it into their own Postman workspace, making it easy to collaborate on API projects.

exporting a collection in postman

Importing Collections: Streamlining Integration

Importing a collection is a straightforward process that allows you to quickly integrate shared collections into your own Postman workspace. Here’s how to do it:

  • Launch Postman and select the “Import” button located in the upper left corner.
  • Choose the source from which you want to import the collection. You can import from a file, link, or even directly from your Postman account if you have collections stored there.
  • Select the collection file or enter the link, and click “Import.”

The imported collection will now be available in your workspace, ready for you to explore, test, and use in your API development tasks.

importing collections in postman

Why Export and Import Matters?

The ability to export and import collections in Postman is a game-changer for teams and individuals alike. It fosters collaboration, allowing you to share your hard work with others and benefit from the work of fellow developers and testers. It streamlines the integration of shared resources, making it a breeze to include external collections in your projects.

Creating Tests in Postman

  • To create a test in Postman, follow these simple steps:
  • Open Postman and create or select a request you want to test.
  • Within the request, go to the “Tests” tab.

Here, you can write JavaScript code to define your test. You can use Postman’s built-in snippets or write custom scripts. These scripts can include assertions, which are statements that define the expected behavior of the API response. For instance, you can check if the response status code is 200 (indicating a successful request). Here’s an example:

pm.test(“Response status code is 200”, function () {
    pm.response.to.have.status(200);
});

These assertions are the core of your tests, setting conditions that must be met for the test to pass.

Collection Runner

collection runners in postman

The Collection Runner in Postman allows you to run your entire collection or a selected set of requests in a sequence, making it easier to test your APIs in a controlled manner. To access the Collection Runner, click on the “Runner” button in the top left corner of the Postman interface.
In the Collection Runner, you can select the collection you want to run, choose the environment, and set other options such as the number of iterations and the delay between requests. Once you have configured the Collection Runner, click on the “Start Run” button to begin the test execution

Workflow Handling

workflow handling in postman

In the world of API development, handling user workflows can be both vital and intricate. Thankfully, Postman, a robust tool designed for API testing and development, simplifies the process. In this, we’ll dive into how Postman enables you to efficiently manage key user-related tasks, including listing users, creating new ones, and updating user information.

1. Listing Users

  • Craft a request to retrieve a user list.
  • Use the “GET” method and set up tests for data validation.
  • Postman’s user-friendly interface simplifies request creation and test automation.

2. Creating Users

  • Create a “POST” request to add new users.
  • Include user data in the request body.
  • Set up tests to confirm successful creation.

3. Updating Users

  • Develop a “PUT” or “PATCH” request for user updates.
  • Include updated user data and verify the response.
  • Postman’s variable management ensures consistency.

Data Driven Approach

Postman’s data-driven approach allows you to test your APIs with different sets of data, making it easier to validate the behavior of your API under various conditions. You can use variables and data files to achieve data-driven testing in Postman.
To use data files in Postman, you can simply import a CSV or JSON file that contains your test data. 

You can then use the variables in your requests and tests to dynamically substitute the imported data, allowing you to execute multiple test scenarios and automate the validation of your API’s behavior with ease.

Pagination in Postman

Pagination is a technique used to manage large datasets, ensuring that data is delivered in manageable portions or “pages.” It’s a common practice in API design, enabling efficient data retrieval without overloading the server or client.

1. Offset Pagination

Offset pagination is one of the most traditional methods. In this approach, the API client requests data with two parameters: “limit” and “offset.” The “limit” parameter defines the number of records to be retrieved on each page, while the “offset” parameter specifies where in the dataset the page starts. Postman excels in handling offset pagination:

Creating Requests: In Postman, you can easily create requests with the necessary parameters. For offset pagination, you’d set the “limit” and “offset” variables accordingly to control the number of records retrieved and the starting point.

Automating Tests: Postman’s scripting capabilities allow you to automate the testing of each paginated request. You can dynamically update the “offset” variable in your tests to ensure comprehensive validation across all pages.

2. Keyset Pagination

Keyset pagination, also known as “cursor pagination,” is a modern alternative to offset pagination. Instead of relying on numerical offsets, it uses unique identifiers (usually a timestamp or a similar attribute) to mark where the next page should begin. Postman is adept at handling keyset pagination:

Configuring Requests: In Postman, you can configure requests to include keyset parameters. These parameters guide the API on where to start the next page.

Validation: When it comes to testing, Postman allows you to efficiently verify the continuity and accuracy of keyset pagination by using scripts to ensure that the keyset in one page corresponds correctly to the next page.

Mock Servers

mock servers in postman

Mock servers are crucial components of API testing and development, allowing developers to simulate API responses without relying on the actual backend infrastructure. In the Postman API Platform, a mock server is a tool that enables you to make API requests and simulate the corresponding responses. This feature is particularly useful when working with external APIs that may not be available during the development process or when multiple teams are working concurrently, causing potential delays and interruptions

Monitoring

Postman’s monitoring feature is the watchful guardian of your APIs, offering real-time insights to ensure they perform seamlessly. With the ability to create and schedule tests, it empowers you to catch issues early, optimize performance, and make data-driven decisions, all within a user-friendly interface. In the fast-paced world of API testing, Postman’s monitoring is your compass for staying on course and maintaining API reliability.

Documentation

Documentation is a crucial aspect of API development, as it helps users understand how to interact with your API and leverage its capabilities. In Postman, you can easily create and publish documentation for your APIs, making it a valuable tool for both developers and consumers. Here’s how you can use Postman to create comprehensive API documentation:

Add Descriptions to Your Documentation 

Start by selecting the desired collection or folder in the Collections sidebar. Then, navigate to the Overview tab and enter a description for your API. This description should provide an overview of your API’s functionality and any important details that users need to know.

Publish Your Documentation

Once you have added the necessary descriptions to your documentation, you can publish it to make it accessible to users. Postman allows you to publish your documentation, making it available to people around the world who want to learn how to use your collection or interact with your Public API. This feature is incredibly useful for sharing your API’s capabilities with a wider audience.

View Complete Documentation

To view the complete documentation for an API, select the API in the sidebar and then choose a collection. From there, you can select “View complete documentation” to see the full documentation for your API. This view provides a comprehensive overview of your API’s endpoints, request parameters, and response structures, making it easy for users to understand how to interact with your API.

By following these steps, you can create detailed and user-friendly documentation for your APIs using Postman. This documentation will help developers and consumers understand how to use your API effectively, leading to better integration and adoption of your API within the developer community.

Newman

what is newman

Efficiency is the name of the game in API testing, and Newman, the command-line tool from Postman, is your secret weapon. Featured in our blog series “How to Use Postman in API Testing,” Newman revolutionizes your testing approach by enabling you to execute Postman collections via the command line. This opens the door to test automation, CI/CD pipeline integration, and seamless scalability. With Newman, you can effortlessly run collections, generate comprehensive reports, and ensure that your APIs are always performing at their best.

Best Practices for Effective API Testing with Postman

In the world of API testing, success hinges on efficiency and precision. To make the most of Postman for your API testing, consider these 8 best practices:

  • Basic Assertions: Start with fundamental checks like status codes to ensure the API behaves as expected.
  • Parameterization: Use variables to test your API with various inputs, saving time and effort.
  • Dynamic Variables: Employ dynamic variables to capture and reuse data from responses.
  • Variable Names/Scope: Maintain well-organized variables with appropriate scope to avoid confusion.
  • Sad Path Testing: Don’t just test for success; explore error scenarios to ensure robustness.
  • Add Path Testing: Expand your tests systematically to cover different aspects of your API.
  • Adding Descriptions: Document your requests and tests to enhance clarity and collaboration.
  • Output Complex Responses: Extract and validate complex data structures from responses to ensure data integrity. With these practices in place, your API testing in Postman becomes a seamless, efficient, and reliable process.

To Conclude

As you venture into the exciting realm of API testing with Postman, remember that practice makes perfect. These simple yet effective best practices, combined with Postman’s user-friendly features, are your secret weapons for a seamless API testing journey. Embrace these insights, supercharge your testing skills, and unlock the door to more reliable software. Stay tuned for more expert tips and tricks as we continue to unravel the power of Postman.

Read the earlier part of this blog that covers the basics in API Testing Tutorial.

Note: This blog is derived from Pricilla Bilavendran’s workshop on Postman with The Test Tribe. Pricilla is a Postman Supernova, an instructor at Thrive EdSchool, and a long-time contributor with The Test Tribe. She has one of the most comprehensive course on Postman API testing at Thrive EdSchool.

Want to connect with the author of this workshop? Check out the links below.

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