Flow creation in Postman - Build an Automation Script

Create and run a simple Postman flow to send a GET request and verify response

Preconditions (3)

Step 1: Open Postman and click on 'Flows' tab

Step 2: Click 'Create Flow' button

Step 3: Drag and drop a 'Request' node onto the canvas

Step 4: Configure the Request node with method GET and URL 'https://jsonplaceholder.typicode.com/posts/1'

Step 5: Drag and drop a 'Test' node onto the canvas

Step 6: Connect the Request node output to the Test node input

Step 7: In the Test node, add a test script to verify the response status code is 200

Step 8: Click 'Run' button to execute the flow

✅ Expected Result: The flow runs successfully, sending the GET request and the test node verifies the response status code is 200, showing a pass result

Automation Requirements - Postman Flows

Assertions Needed:

Verify response status code is 200

Best Practices:

Use clear and descriptive node names

Connect nodes logically to represent flow

Use built-in test scripts for assertions

Keep flow simple and modular

Automated Solution

Postman

const pm = require('postman-collection');

// Create a new flow
const flow = new pm.Flow({
  name: 'Simple GET Request Flow'
});

// Create a request node
const requestNode = flow.addNode('Request', {
  method: 'GET',
  url: 'https://jsonplaceholder.typicode.com/posts/1'
});

// Create a test node
const testNode = flow.addNode('Test', {
  testScript: `pm.test('Status code is 200', function () {
    pm.response.to.have.status(200);
});`
});

// Connect request node to test node
flow.connect(requestNode, testNode);

// Run the flow
flow.run().then(() => {
  console.log('Flow executed successfully');
}).catch(err => {
  console.error('Flow execution failed:', err);
});

This script creates a Postman flow programmatically.

First, it creates a new flow named 'Simple GET Request Flow'.

Then, it adds a Request node configured to send a GET request to the specified URL.

Next, it adds a Test node with a test script that checks if the response status code is 200.

The Request node is connected to the Test node to ensure the test runs after the request.

Finally, the flow is executed with flow.run(), and success or failure is logged.

This approach follows best practices by keeping nodes clear and connecting them logically.

Common Mistakes - 3 Pitfalls

Not connecting the Request node to the Test node

Hardcoding URLs without using variables

Writing test scripts outside the Test node

Bonus Challenge

Now add data-driven testing with 3 different URLs to send GET requests and verify status 200

Show Hint

Practice

1. What is the main purpose of creating a flow in Postman?

easy

A. To automate API tests by chaining multiple requests

B. To write SQL queries inside Postman

C. To design user interfaces for APIs

D. To create database backups automatically

Solution

1. Step 1: Understand flow creation in Postman

   Flow creation means linking API requests so they run one after another automatically.

2. Step 2: Identify the purpose of chaining requests

   Chaining helps automate tests by passing data between requests and checking responses.

3. Final Answer:

   To automate API tests by chaining multiple requests -> Option A

4. Quick Check:

   Flow creation = automate chained API tests [OK]

Hint: Flows chain requests to automate tests quickly [OK]

Common Mistakes:

• Confusing flow creation with UI design
• Thinking flow creates database backups
• Assuming flow writes SQL queries

2. Which Postman script section is used to pass data from one request to the next in a flow?

easy

A. Pre-request Script

B. Headers

C. Tests

D. Body

Solution

1. Step 1: Identify where to save data after a request

   The Tests script runs after a request and can save response data to variables.

2. Step 2: Understand data passing in flows

   Saved variables from Tests can be used in the next request's Pre-request Script or URL.

3. Final Answer:

   Tests -> Option C

4. Quick Check:

   Data passing happens in Tests script [OK]

Hint: Use Tests to save data for next request [OK]

Common Mistakes:

• Using Body to pass data between requests
• Confusing Pre-request Script as data saver
• Trying to pass data via Headers

3. Consider this Postman Tests script snippet:
pm.environment.set('token', pm.response.json().access_token);
What will be the value of token after this runs if the response JSON is {"access_token": "abc123"}?

medium

A. undefined

B. "abc123"

C. pm.response.json()

D. null

Solution

1. Step 1: Extract value from response JSON

   The code accesses the 'access_token' key from the JSON response, which is "abc123".

2. Step 2: Store value in environment variable

   pm.environment.set saves "abc123" as the value of 'token'.

3. Final Answer:

   "abc123" -> Option B

4. Quick Check:

   token = "abc123" after set [OK]

Hint: pm.environment.set stores exact JSON key value [OK]

Common Mistakes:

• Assuming token becomes undefined
• Confusing the whole JSON with the value
• Expecting null instead of actual token

4. You wrote this Pre-request Script to use a token saved in environment variables:
pm.request.headers.add({key: 'Authorization', value: 'Bearer ' + pm.environment.get('token')});
But the API returns 401 Unauthorized. What is the likely error?

medium

A. Bearer keyword should be lowercase 'bearer'

B. The header key should be lowercase 'authorization'

C. pm.request.headers.add is not valid syntax

D. The token variable is not set or is empty

Solution

1. Step 1: Check if token variable exists

   If 'token' is missing or empty, the Authorization header will be invalid.

2. Step 2: Verify header syntax and casing

   Header keys are case-insensitive, and 'Bearer' is case-sensitive but usually uppercase works fine.

3. Step 3: Confirm method usage

   pm.request.headers.add is valid to add headers dynamically.

4. Final Answer:

   The token variable is not set or is empty -> Option D

5. Quick Check:

   Missing token causes 401 Unauthorized [OK]

Hint: Check if token variable is set before request [OK]

Common Mistakes:

• Changing header key case unnecessarily
• Lowercasing 'Bearer' keyword
• Thinking pm.request.headers.add is invalid

5. You want to create a flow where the first request logs in and saves a token, and the second request uses that token in its header. Which steps correctly describe this flow setup?

hard

A. In first request Tests, save token to environment; in second request Pre-request Script, add Authorization header using saved token

B. In first request Body, save token; in second request Tests, add Authorization header

C. In first request Headers, save token; in second request Body, add Authorization header

D. In first request Pre-request Script, save token; in second request Tests, add Authorization header

Solution

1. Step 1: Save token after login request

   Use Tests script in first request to extract token from response and save it to environment variables.

2. Step 2: Use token before second request

   In second request's Pre-request Script, read the saved token and add it to the Authorization header.

3. Final Answer:

   In first request Tests, save token to environment; in second request Pre-request Script, add Authorization header using saved token -> Option A

4. Quick Check:

   Save token in Tests, use in Pre-request Script [OK]

Hint: Save token in Tests, use in Pre-request Script for next request [OK]

Common Mistakes:

• Trying to save token in Body or Headers
• Adding header in Tests instead of Pre-request Script
• Saving token before request runs