Saving responses in Postman - Test Execution Trace

Test Overview

This test sends a GET request to an API endpoint and saves the response body into a Postman environment variable. It then verifies that the response status is 200 and that the saved response matches the actual response.

Test Code - Postman

Postman

pm.test("Status code is 200", function () {
    pm.response.to.have.status(200);
});

pm.test("Save response body to environment variable", function () {
    let responseBody = pm.response.text();
    pm.environment.set("savedResponse", responseBody);
    pm.expect(pm.environment.get("savedResponse")).to.eql(responseBody);
});

Execution Trace - 5 Steps

Step	Action	System State	Assertion	Result
1	Send GET request to the API endpoint	Postman sends the request and waits for response	—	PASS
2	Check that response status code is 200	Response received with status code 200	Verify pm.response.to.have.status(200)	PASS
3	Extract response body as text	Response body is available as string	—	PASS
4	Save response body to environment variable 'savedResponse'	Environment variable 'savedResponse' is set with response text	—	PASS
5	Verify saved environment variable matches response body	Environment variable value equals response body text	pm.expect(pm.environment.get('savedResponse')).to.eql(responseBody)	PASS

Failure Scenario

Failing Condition: Response status is not 200 or environment variable is not set correctly

Execution Trace Quiz - 3 Questions

What does the test verify first after sending the request?

A That the response body is empty

B That the environment variable is deleted

C That the response status code is 200

D That the request method is POST

Key Result

Always verify the response status before saving data, and confirm saved variables match the actual response to avoid false positives.

Practice

1. What is the main purpose of saving responses in Postman?

easy

A. To speed up the API server

B. To delete old API requests automatically

C. To keep track of API outputs for later use

D. To change the API endpoint URL

Solution

1. Step 1: Understand the role of saving responses

   Saving responses allows testers to keep the output data from API calls for future reference or validation.

2. Step 2: Identify the correct purpose

   Among the options, only keeping track of API outputs matches the purpose of saving responses.

3. Final Answer:

   To keep track of API outputs for later use -> Option C

4. Quick Check:

   Saving responses = keep API outputs [OK]

Hint: Saving responses means storing API outputs for reuse [OK]

Common Mistakes:

• Confusing saving responses with deleting requests
• Thinking it speeds up the server
• Assuming it changes API URLs

2. Which Postman script command is used to save a value from a response into an environment variable?

easy

A. pm.response.save()

B. pm.environment.set()

C. pm.request.store()

D. pm.variable.get()

Solution

1. Step 1: Recall Postman scripting commands

   To save data into environment variables, Postman uses the command pm.environment.set(variableName, value).

2. Step 2: Match the command to the options

   Only pm.environment.set() correctly saves a value into an environment variable.

3. Final Answer:

   pm.environment.set() -> Option B

4. Quick Check:

   Save to environment = pm.environment.set() [OK]

Hint: Use pm.environment.set() to save response data [OK]

Common Mistakes:

• Using pm.response.save() which does not exist
• Confusing get() with set()
• Trying to save with pm.request.store() which is invalid

3. Given this Postman test script, what will be the value saved in the environment variable 'userId' if the response JSON is {"id": 42, "name": "Alice"}?

let jsonData = pm.response.json();
pm.environment.set('userId', jsonData.id);

medium

A. 42

B. null

C. undefined

D. "Alice"

Solution

1. Step 1: Parse the response JSON

   The response JSON has an "id" field with value 42 and a "name" field with "Alice".

2. Step 2: Check the script saving the value

   The script saves jsonData.id into 'userId', so it saves 42.

3. Final Answer:

   42 -> Option A

4. Quick Check:

   jsonData.id = 42 [OK]

Hint: jsonData.id saves the number 42 from response [OK]

Common Mistakes:

• Saving the name instead of id
• Assuming undefined if JSON parsing fails
• Confusing string and number values

4. You wrote this test script to save a token from response but it does not save correctly:

let jsonData = pm.response.json();
pm.environment.set('token', jsonData.token);

What is a likely reason the token is not saved?

medium

A. The response does not contain a 'token' field

B. pm.environment.set() is not a valid function

C. You must use pm.response.save() instead

D. The variable name 'token' is reserved

Solution

1. Step 1: Check the response JSON fields

   If the response JSON does not have a 'token' field, jsonData.token will be undefined.

2. Step 2: Understand saving undefined values

   Saving undefined means the environment variable 'token' will not be set correctly.

3. Final Answer:

   The response does not contain a 'token' field -> Option A

4. Quick Check:

   Missing field = no saved value [OK]

Hint: Check response fields before saving variables [OK]

Common Mistakes:

• Thinking pm.environment.set() is invalid
• Using non-existent pm.response.save()
• Assuming variable names are reserved

5. You want to save the 'sessionId' from a nested JSON response:

{
  "user": {
    "id": 10,
    "session": {
      "sessionId": "abc123"
    }
  }
}

Which script correctly saves 'sessionId' into an environment variable?

hard

A. let jsonData = pm.response.json(); pm.environment.set('sessionId', jsonData.user.session['id']);

B. let jsonData = pm.response.json(); pm.environment.set('sessionId', jsonData.sessionId);

C. let jsonData = pm.response.json(); pm.environment.set('sessionId', jsonData.user.sessionId);

D. let jsonData = pm.response.json(); pm.environment.set('sessionId', jsonData.user.session.sessionId);

Solution

1. Step 1: Analyze the JSON structure

   The 'sessionId' is inside user > session > sessionId.

2. Step 2: Match the correct path in script

   Only jsonData.user.session.sessionId correctly accesses the nested 'sessionId'.

3. Final Answer:

   let jsonData = pm.response.json(); pm.environment.set('sessionId', jsonData.user.session.sessionId); -> Option D

4. Quick Check:

   Nested access = jsonData.user.session.sessionId [OK]

Hint: Use full path for nested JSON fields [OK]

Common Mistakes:

• Accessing sessionId directly from jsonData
• Using wrong nested keys
• Confusing sessionId with user id