Using Postman to automate a series of API requests is a game-changer for developers and testers. Postman allows you to encapsulate multiple requests in a collection and then run those requests sequentially. Below is a step-by-step guide on how to create a simple Postman script to run a sequence of requests.

Step 1: Setting Up Your Collection

1. Open Postman: Launch the Postman application on your computer.

2. Create a New Collection:

   • Click on the "New" button on the top-left corner.
   • Choose "Collection" from the dropdown.
   • Name your collection, e.g., "User Management API".

3. Add Requests:

   • Click on your newly created collection.
   • Click the "Add Request" button.
   • Name your requests, for example, "Create User", "Get User", and "Delete User".
   • Define the HTTP method and URL for each request according to your API specifications.

Step 2: Defining Interdependencies

In many cases, the output of one request needs to feed into the next. For example, the "Create User" request needs to provide a user ID for the "Get User" request.

1. Create User Request:

   • Select your "Create User" request.
   • In the "Tests" tab, write a script to extract the user ID from the response:

     const response = pm.response.json();
     pm.environment.set("userId", response.id); // Assuming your response has an 'id' field

2. Get User Request:

   • Select your "Get User" request.
   • Configure it to use the extracted user ID:
     • Set the URL to https://api.example.com/users/{{userId}}
   • Ensure that you have an environment variable named userId.

3. Delete User Request:

   • Similarly, follow the same steps to set the URL for the "Delete User" request:
     • Set the URL to https://api.example.com/users/{{userId}}

Step 3: Running the Requests in Sequence

The next step is to use Postman Runner to execute these requests sequentially.

1. Open Collection Runner:

   • Go to the collection you created.
   • Click on the “Runner” button on the top right of the collection view.

2. Select Requests:

   • Choose your collection which contains the requests.
   • Ensure that the requests you want to run are selected.

3. Run the Collection:

   • Click the “Run” button. It will execute the requests one after the other, with the environment variable userId being updated dynamically after the "Create User" request.

Step 4: Observing the Output

As the requests run, you'll see the results of each step in the runner's interface. If you scripted your requests correctly, each request should follow logically from the previous one.

This setup ensures a reliable and automated testing workflow, crucial for any development environment.

Additional Tips

• Environment Variables: Use them wisely to keep your requests dynamic and cleaner. They help in passing information easily between requests.
• Error Handling: Implement appropriate error handling in your tests to ensure that your sequence stops if one of the requests fails, preventing cascading errors.
• Documentation: Keep your collection well-documented within Postman itself. Add descriptions for each request and their purpose.

By following these steps, you can effectively use Postman to run a sequence of API requests, automating a normally tedious task and ensuring a smoother workflow in your development cycle.