Run order and flow control in Postman - Test Execution Trace

Test Overview

This test demonstrates the default sequential order in which Postman requests run within a collection and shows that simply setting environment variables does not automatically manage flow control or conditional execution.

Test Code - Postman

Postman

pm.test("First request runs", function () {
    pm.expect(true).to.be.true;
});

// Set a variable to control flow
pm.environment.set("runNext", "second");

// Second request test script:
pm.test("Second request runs only if runNext is 'second'", function () {
    pm.expect(pm.environment.get("runNext")).to.eql("second");
});

// Change variable to stop further requests
pm.environment.set("runNext", "stop");

// Third request test script:
pm.test("Third request should not run if runNext is 'stop'", function () {
    pm.expect(pm.environment.get("runNext")).to.not.eql("stop");
});

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Start collection run in Postman	Postman collection runner opens with three requests queued	—	PASS
2	Run first request and execute its test script	First request response received	Check that the test 'First request runs' passes	PASS
3	Set environment variable 'runNext' to 'second'	Environment variable 'runNext' is set to 'second'	—	PASS
4	Run second request and execute its test script	Second request response received	Verify 'runNext' equals 'second' in test script	PASS
5	Set environment variable 'runNext' to 'stop'	Environment variable 'runNext' is set to 'stop'	—	PASS
6	Attempt to run third request and execute its test script	Third request response received	Check that 'runNext' is not 'stop' (expected to fail)	FAIL

Failure Scenario

Failing Condition: Third request runs even though 'runNext' is set to 'stop', causing assertion failure

Execution Trace Quiz - 3 Questions

What controls the order of requests in this Postman test?

A Environment variable 'runNext' set in test scripts

B The order requests are listed in the collection only

C Random selection by Postman

D Manual user clicks during run

Key Result

Postman runs collection requests sequentially by default. Control run order and skip conditionally using postman.setNextRequest(name or null) in test/pre-request scripts or pm.execution.skip() in pre-request scripts, driven by environment variables if needed.

Practice

1. In Postman, what does pm.setNextRequest() do in a collection run?

easy

A. It sets which request runs next in the collection.

B. It stops the entire collection run immediately.

C. It restarts the current request.

D. It logs the response of the current request.

Solution

1. Step 1: Understand the purpose of pm.setNextRequest()

   This function controls the flow by specifying the next request to run in the collection.

2. Step 2: Compare other options

   Stopping the run is done by pm.setNextRequest(null), not this function. Restarting or logging are unrelated.

3. Final Answer:

   It sets which request runs next in the collection. -> Option A

4. Quick Check:

   Flow control = set next request [OK]

Hint: Remember: setNextRequest controls next request flow [OK]

Common Mistakes:

• Confusing pm.setNextRequest() with stopping the run
• Thinking it restarts the current request
• Assuming it logs data instead of controlling flow

2. Which of the following is the correct syntax to stop running any further requests in a Postman collection?

easy

A. pm.abortRun()

B. pm.setNextRequest('stop')

C. pm.stopCollection()

D. pm.setNextRequest(null)

Solution

1. Step 1: Identify the method to stop collection run

   Postman uses pm.setNextRequest(null) to stop running further requests.

2. Step 2: Verify other options

   Other options like pm.stopCollection() or pm.abortRun() do not exist in Postman scripting.

3. Final Answer:

   pm.setNextRequest(null) -> Option D

4. Quick Check:

   Stop run = setNextRequest(null) [OK]

Hint: Use null in setNextRequest to stop run [OK]

Common Mistakes:

• Using a string like 'stop' instead of null
• Assuming non-existent functions stop the run
• Confusing stopping with skipping requests

3. Consider this Postman test script inside a request named 'Request A':

if (pm.response.code === 200) {
  pm.setNextRequest('Request B');
} else {
  pm.setNextRequest(null);
}

What happens if the response code is 404?

medium

A. The collection run continues to 'Request B'.

B. An error is thrown and the run fails.

C. The collection run stops after 'Request A'.

D. The collection run restarts from the first request.

Solution

1. Step 1: Analyze the condition for response code 404

   Since 404 is not 200, the else block runs pm.setNextRequest(null).

2. Step 2: Understand effect of pm.setNextRequest(null)

   This stops the collection run immediately after the current request.

3. Final Answer:

   The collection run stops after 'Request A'. -> Option C

4. Quick Check:

   404 triggers stop = setNextRequest(null) [OK]

Hint: If condition false, setNextRequest(null) stops run [OK]

Common Mistakes:

• Assuming it continues to next request regardless
• Thinking it restarts the collection
• Believing an error is thrown automatically

4. You wrote this test script in Postman:

pm.setNextRequest('Request C');
pm.setNextRequest(null);

What is the effect on the collection run flow?

medium

A. The run jumps to 'Request C' and then stops.

B. The run stops immediately; 'Request C' is skipped.

C. The run ignores both commands and continues normally.

D. The run loops infinitely between requests.

Solution

1. Step 1: Understand order of pm.setNextRequest calls

   Only the last pm.setNextRequest() call takes effect in a single script execution.

2. Step 2: Analyze the last call pm.setNextRequest(null)

   This stops the collection run immediately, ignoring previous setNextRequest calls.

3. Final Answer:

   The run stops immediately; 'Request C' is skipped. -> Option B

4. Quick Check:

   Last setNextRequest call wins = null stops run [OK]

Hint: Last setNextRequest call controls flow [OK]

Common Mistakes:

• Thinking both calls run in sequence
• Assuming first call overrides last
• Believing it causes infinite loops

5. You want to run a Postman collection where:
- If 'Login' request succeeds (status 200), run 'GetData'.
- If 'Login' fails, stop the run.
- After 'GetData', always run 'Logout'.

Which sequence of pm.setNextRequest() calls in the 'Login' and 'GetData' test scripts achieves this flow?

hard

A. In 'Login': pm.setNextRequest('GetData') if 200 else pm.setNextRequest(null);In 'GetData': pm.setNextRequest('Logout')

B. In 'Login': pm.setNextRequest('Logout') always;In 'GetData': pm.setNextRequest(null)

C. In 'Login': pm.setNextRequest(null) always;In 'GetData': pm.setNextRequest('Logout')

D. In 'Login': pm.setNextRequest('GetData') always;In 'GetData': pm.setNextRequest(null)

Solution

1. Step 1: Control flow after 'Login'

   If status is 200, next request should be 'GetData'; else stop run with pm.setNextRequest(null).

2. Step 2: Control flow after 'GetData'

   Always run 'Logout' next, so pm.setNextRequest('Logout') is set in 'GetData' tests.

3. Final Answer:

   In 'Login': pm.setNextRequest('GetData') if 200 else pm.setNextRequest(null); In 'GetData': pm.setNextRequest('Logout') -> Option A

4. Quick Check:

   Conditional jump + final logout = In 'Login': pm.setNextRequest('GetData') if 200 else pm.setNextRequest(null);
   In 'GetData': pm.setNextRequest('Logout') [OK]

Hint: Use conditional setNextRequest in Login, fixed next in GetData [OK]

Common Mistakes:

• Setting wrong next request after Login
• Not stopping run on Login failure
• Skipping Logout after GetData