Running a collection in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ query_result

intermediate

What is the output count after running this Postman collection?

You have a Postman collection with 3 requests. Each request returns a JSON response with a field status. The collection runs sequentially and you use a test script to count how many responses have status equal to success.

After running the collection, what is the value of the counter if the responses are: {"status": "success"}, {"status": "fail"}, {"status": "success"}?

Postman

let successCount = Number(pm.environment.get('successCount') || 0);
pm.test('Count success status', function () {
    let jsonData = pm.response.json();
    if (jsonData.status === 'success') {
        successCount++;
    }
    pm.environment.set('successCount', successCount);
});

A 1

B 2

C 0

D 3

💡 Hint

Count only responses where status is exactly success.

Only the first and third responses have status equal to success, so the count is 2.

🧠 Conceptual

intermediate

Which environment variable scope is best for sharing data across all requests in a collection run?

You want to store a variable in Postman that is accessible by all requests during a collection run but does not persist after the run ends. Which variable scope should you use?

A Global variable

B Environment variable

C Collection variable

D Local variable

💡 Hint

Think about variables that exist only during the collection run and are shared by all requests in that collection.

Collection variables exist only during the collection run and are shared by all requests in that collection. Environment and global variables persist beyond the run.

📝 Syntax

advanced

Identify the syntax error in this Postman test script snippet

What error does this Postman test script produce?

pm.test('Response has userId', () => {
  let jsonData = pm.response.json()
  pm.expect(jsonData.userId).to.eql(123);
});

A No error, script runs successfully

B TypeError: pm.expect is not a function

C SyntaxError: Missing semicolon after pm.response.json()

D ReferenceError: jsonData is not defined

💡 Hint

Check if the code syntax and function calls are correct.

The code uses arrow function syntax correctly and calls pm.expect properly. Missing semicolons are optional in JavaScript and do not cause errors here.

❓ optimization

advanced

How to optimize running a large collection with many requests?

You have a Postman collection with 100 requests. Running it sequentially takes a long time. Which approach optimizes the total run time?

A Disable tests to speed up execution

B Add delays between requests to avoid server overload

C Split the collection into smaller collections and run them one after another

D Run requests in parallel using Postman Runner's concurrency setting

💡 Hint

Think about running multiple requests at the same time.

Postman Runner allows setting concurrency to run multiple requests in parallel, reducing total run time.

🔧 Debug

expert

Why does this collection run fail to update the variable as expected?

In a collection run, you try to increment a variable counter in the test script of each request like this:

let count = pm.variables.get('counter');
count++;
pm.variables.set('counter', count);

But after the run, counter remains unchanged. Why?

A pm.variables.get() returns undefined because 'counter' is not set initially

B pm.variables.get() returns a string, so incrementing causes NaN

C pm.variables.set() updates only local variables, not environment or collection variables

D pm.variables.set() cannot update variables during collection run

💡 Hint

Check if the variable exists before incrementing.

If 'counter' is not set initially, pm.variables.get('counter') returns undefined. Incrementing undefined results in NaN, so the variable is not updated properly.

Practice

1. What is the main purpose of Running a collection in Postman?

easy

A. To write code for APIs

B. To create new API endpoints

C. To execute a group of API requests in a specific order

D. To delete saved requests

Solution

1. Step 1: Understand what a collection is

   A collection in Postman is a group of API requests organized together.

2. Step 2: Purpose of running a collection

   Running a collection means executing all requests in that group one after another automatically.

3. Final Answer:

   To execute a group of API requests in a specific order -> Option C

4. Quick Check:

   Running a collection = executing grouped requests [OK]

Hint: Running a collection means running all requests together [OK]

Common Mistakes:

• Confusing running a collection with creating requests
• Thinking it deletes requests
• Assuming it writes code automatically

2. Which of the following is the correct way to start running a collection in Postman?

easy

A. Drag the collection to the trash bin

B. Right-click the collection and select 'Delete'

C. Open the collection and edit the request

D. Click the 'Run' button on the collection

Solution

1. Step 1: Locate the collection in Postman

   Collections appear in the sidebar with a 'Run' button visible when selected.

2. Step 2: Starting the run

   Clicking the 'Run' button starts executing all requests in the collection.

3. Final Answer:

   Click the 'Run' button on the collection -> Option D

4. Quick Check:

   Run button starts collection execution [OK]

Hint: Look for the 'Run' button to start collections [OK]

Common Mistakes:

• Choosing delete instead of run
• Editing requests does not run collection
• Dragging to trash deletes collection

3. Given a collection with 3 requests, if you run the collection and the second request fails, what happens next?

medium

A. The collection stops running immediately

B. The collection continues to run the third request

C. The collection retries the second request automatically

D. The collection deletes the failed request

Solution

1. Step 1: Understand default run behavior

   By default, Postman runs all requests in a collection sequentially regardless of individual request failures.

2. Step 2: Effect of a failed request

   A failed request does not stop the collection run; it moves on to the next request.

3. Final Answer:

   The collection continues to run the third request -> Option B

4. Quick Check:

   Collection runs all requests even if one fails [OK]

Hint: Collection runs all requests unless manually stopped [OK]

Common Mistakes:

• Assuming run stops on failure
• Thinking Postman retries automatically
• Believing failed requests get deleted

4. You try to run a collection but get an error saying 'No requests found'. What is the likely cause?

medium

A. The collection is empty with no requests inside

B. You have not selected any environment

C. Postman is offline

D. You clicked 'Run' on a single request instead of collection

Solution

1. Step 1: Analyze the error message

   'No requests found' means the collection has no requests to run.

2. Step 2: Check collection contents

   If the collection is empty, running it will cause this error.

3. Final Answer:

   The collection is empty with no requests inside -> Option A

4. Quick Check:

   Empty collection = no requests to run error [OK]

Hint: Check if collection has requests before running [OK]

Common Mistakes:

• Confusing environment selection with requests
• Assuming offline causes this error
• Thinking running single request triggers this

5. You want to run a collection multiple times with different data sets for each run. Which Postman feature helps you do this efficiently?

hard

A. Using a data file with the Collection Runner

B. Manually editing each request before running

C. Running each request separately

D. Duplicating the collection for each data set

Solution

1. Step 1: Identify the need for multiple data sets

   Running the same collection with different inputs requires data-driven testing.

2. Step 2: Use Collection Runner with data files

   Postman allows uploading CSV or JSON files to run collections multiple times with varied data.

3. Final Answer:

   Using a data file with the Collection Runner -> Option A

4. Quick Check:

   Data files + Collection Runner = multiple runs with different data [OK]

Hint: Use data files in Collection Runner for repeated tests [OK]

Common Mistakes:

• Editing requests manually wastes time
• Running requests separately is inefficient
• Duplicating collections is unnecessary