Delay between requests in Postman - Test Execution Trace

Test Overview

This test checks if a delay is correctly applied between two API requests in Postman. It verifies that the second request waits for the specified time before sending using a busy-wait loop in the pre-request script.

Test Code - Postman

Postman

pm.test("Delay between requests", function () {
    const startTime = new Date().getTime();
    pm.environment.set("startTime", startTime);
});

// In the second request's Pre-request Script:
const startTime = parseInt(pm.environment.get("startTime"));
const delay = 3000; // 3 seconds delay
const targetTime = startTime + delay;
console.log(`Target send time: ${targetTime}`);

while (new Date().getTime() < targetTime) {
    // Busy-wait loop to delay request sending
}
console.log(`Delay applied. Sending request after at least ${delay} ms.`);

// In the second request's Tests script:
pm.test("Request sent after delay", function () {
    const responseTime = new Date().getTime();
    const startTime = parseInt(pm.environment.get("startTime"));
    const delay = 3000;
    pm.expect(responseTime - startTime).to.be.at.least(delay);
});

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	First request's Tests script records current time in environment variable 'startTime'.	Postman environment variable 'startTime' set to timestamp after first request completes.	—	PASS
2	Second request's Pre-request Script reads 'startTime' and calculates targetTime = startTime + 3000ms.	Pre-request script prepares for busy-wait delay.	—	PASS
3	Script enters while loop, busy-waiting until current time >= targetTime.	Request sending blocked until exactly 3 seconds from startTime.	—	PASS
4	After busy-wait completes, second request is sent.	Request sent to API endpoint after enforced delay.	—	PASS
5	Second request's Tests script verifies total time elapsed.	Test confirms at least 3000ms passed since startTime (includes delay + response time).	Assert that (responseTime - startTime) >= 3000 ms.	PASS

Failure Scenario

Failing Condition: The delay is not applied or is shorter than 3000 ms between requests (e.g., no busy-wait or incorrect logic).

Execution Trace Quiz - 3 Questions

What does the first request do to help enforce the delay?

A It sends two requests at once.

B It waits for 3 seconds before sending.

C It saves the current time in an environment variable.

D It disables the delay for the second request.

Key Result

Using environment variables and a busy-wait loop in Pre-request Scripts enables precise delays between sequential requests in Postman Collection Runner. Note: Busy-wait consumes CPU; suitable for short test delays. For production, consider runner-level delays.

Practice

1. What is the main purpose of adding a delay between requests in Postman?

easy

A. To change the request URL dynamically

B. To speed up the test execution

C. To skip some requests automatically

D. To simulate real user behavior and avoid server overload

Solution

1. Step 1: Understand delay usage in Postman

   Delays are used to mimic real user wait times and prevent sending too many requests too fast.

2. Step 2: Identify the correct purpose

   Speeding up tests or skipping requests are not related to delays; delays help simulate real scenarios and protect servers.

3. Final Answer:

   To simulate real user behavior and avoid server overload -> Option D

4. Quick Check:

   Delay purpose = simulate real use and avoid overload [OK]

Hint: Delays mimic real users and protect servers from overload [OK]

Common Mistakes:

• Thinking delays speed up tests
• Confusing delay with skipping requests
• Assuming delay changes request data

2. Which of the following is the correct way to add a 2-second delay between requests in Postman using JavaScript?

easy

A. delay(2000); postman.setNextRequest('Request2');

B. postman.setNextRequest('Request2', 2000);

C. setTimeout(() => postman.setNextRequest('Request2'), 2000);

D. setTimeout(postman.setNextRequest('Request2'), 2000);

Solution

1. Step 1: Recall correct setTimeout syntax

   setTimeout takes a function and delay in milliseconds: setTimeout(function, delay).

2. Step 2: Check usage with postman.setNextRequest

   postman.setNextRequest must be called inside a function passed to setTimeout to delay execution.

3. Final Answer:

   setTimeout(() => postman.setNextRequest('Request2'), 2000); -> Option C

4. Quick Check:

   Use setTimeout with function and delay [OK]

Hint: Wrap setNextRequest in a function inside setTimeout [OK]

Common Mistakes:

• Passing setNextRequest call directly to setTimeout
• Using non-existent delay function
• Trying to pass delay as second argument to setNextRequest

3. Given this Postman test script snippet, what will happen?

setTimeout(() => postman.setNextRequest('Login'), 3000);
console.log('Request scheduled');

medium

A. The 'Login' request will run immediately, and 'Request scheduled' logs after 3 seconds

B. 'Request scheduled' logs immediately, and 'Login' request runs after 3 seconds

C. Both 'Login' request and log happen immediately

D. Neither 'Login' request nor log will run

Solution

1. Step 1: Understand setTimeout behavior

   setTimeout delays the function call (postman.setNextRequest) by 3000 ms, but console.log runs immediately.

2. Step 2: Determine order of execution

   console.log('Request scheduled') runs first; after 3 seconds, the 'Login' request is set to run next.

3. Final Answer:

   'Request scheduled' logs immediately, and 'Login' request runs after 3 seconds -> Option B

4. Quick Check:

   console.log immediate, setNextRequest delayed [OK]

Hint: console.log runs immediately; setNextRequest delayed by setTimeout [OK]

Common Mistakes:

• Assuming setNextRequest runs immediately
• Thinking console.log waits for delay
• Confusing order of asynchronous calls

4. You wrote this Postman script to delay the next request by 1 second, but the delay does not work. What is wrong?

setTimeout(postman.setNextRequest('NextRequest'), 1000);

medium

A. postman.setNextRequest should be inside a function passed to setTimeout

B. Delay time should be in seconds, not milliseconds

C. setTimeout cannot be used in Postman scripts

D. postman.setNextRequest does not accept request names

Solution

1. Step 1: Analyze setTimeout usage

   setTimeout expects a function as first argument, but here postman.setNextRequest is called immediately.

2. Step 2: Correct usage for delay

   Wrap postman.setNextRequest call inside a function (e.g., arrow function) to delay execution properly.

3. Final Answer:

   postman.setNextRequest should be inside a function passed to setTimeout -> Option A

4. Quick Check:

   Pass function to setTimeout, not direct call [OK]

Hint: Wrap setNextRequest call in a function for setTimeout delay [OK]

Common Mistakes:

• Passing direct call instead of function to setTimeout
• Confusing milliseconds with seconds
• Believing setTimeout is unsupported in Postman

5. You want to run three requests in sequence with a 1-second delay between each in Postman. Which script correctly implements this in the Tests tab of the first request?

hard

A. setTimeout(() => { postman.setNextRequest('Request2'); setTimeout(() => postman.setNextRequest('Request3'), 1000); }, 1000);

B. setTimeout(() => postman.setNextRequest('Request2'), 1000);

C. postman.setNextRequest('Request2'); setTimeout(() => postman.setNextRequest('Request3'), 1000);

D. postman.setNextRequest('Request2'); postman.setNextRequest('Request3');

Solution

1. Step 1: Understand sequential delays

   Each request must be delayed before triggering the next; nested setTimeout calls create sequential delays.

2. Step 2: Analyze options

   setTimeout(() => { postman.setNextRequest('Request2'); setTimeout(() => postman.setNextRequest('Request3'), 1000); }, 1000); nests setTimeout calls to delay Request2 by 1s, then Request3 by another 1s, correctly sequencing requests with delays.

3. Final Answer:

   setTimeout(() => { postman.setNextRequest('Request2'); setTimeout(() => postman.setNextRequest('Request3'), 1000); }, 1000); -> Option A

4. Quick Check:

   Nested setTimeouts create sequential delays [OK]

Hint: Use nested setTimeouts to delay multiple requests sequentially [OK]

Common Mistakes:

• Calling setNextRequest multiple times without delay
• Not nesting delays causing immediate requests
• Assuming one setTimeout delays all requests