Local variables in Postman - Test Execution Trace

Test Overview

This test checks if a local variable set within a Postman request script is correctly assigned and used in an assertion to verify the response status code.

Test Code - Postman

Postman

pm.test("Status code is 200", function () {
    let expectedStatus = 200; // local variable
    pm.response.to.have.status(expectedStatus);
});

Execution Trace - 4 Steps

Step	Action	System State	Assertion	Result
1	Test script starts execution	Postman request has completed and response is available	—	PASS
2	Local variable 'expectedStatus' is assigned the value 200	Variable 'expectedStatus' holds 200 within the test function scope	—	PASS
3	Assertion checks if response status equals 'expectedStatus' (200)	Response status code is 200	pm.response.to.have.status(expectedStatus)	PASS
4	Test completes successfully	Test result recorded as pass	—	PASS

Failure Scenario

Failing Condition: Response status code is not 200

Execution Trace Quiz - 3 Questions

What does the local variable 'expectedStatus' represent in the test?

A The expected HTTP status code to verify

B The actual response status code

C The response body content

D The request URL

Key Result

Using local variables in test scripts helps keep assertions clear and maintainable by avoiding hard-coded values.

Practice

1. What is the main purpose of local variables in Postman?

easy

A. To create global environment settings

B. To save data permanently across all requests

C. To share data between different collections

D. To store data only during a single request execution

Solution

1. Step 1: Understand local variable scope

   Local variables exist only during the execution of one request and are not saved beyond that.

2. Step 2: Compare with other variable types

   Global or environment variables persist beyond one request, unlike local variables.

3. Final Answer:

   To store data only during a single request execution -> Option D

4. Quick Check:

   Local variables = single request scope [OK]

Hint: Local variables last only during one request [OK]

Common Mistakes:

• Confusing local variables with global variables
• Thinking local variables persist across requests
• Assuming local variables share data between collections

2. Which of the following is the correct syntax to set a local variable named token with value abc123 in Postman?

easy

A. pm.local.set('token', 'abc123');

B. pm.environment.set('token', 'abc123');

C. pm.variables.set('token', 'abc123');

D. pm.globals.set('token', 'abc123');

Solution

1. Step 1: Identify the correct method for local variables

   Local variables use pm.variables.set to assign values.

2. Step 2: Check other options for correctness

   pm.environment.set and pm.globals.set set environment and global variables, not local. pm.local.set is invalid.

3. Final Answer:

   pm.variables.set('token', 'abc123'); -> Option C

4. Quick Check:

   Set local variable = pm.variables.set [OK]

Hint: Use pm.variables.set() for local variables [OK]

Common Mistakes:

• Using pm.environment.set instead of pm.variables.set
• Trying to use pm.local.set which does not exist
• Confusing global and local variable methods

3. Consider this Postman test script:

pm.variables.set('count', 5);
pm.variables.set('count', pm.variables.get('count') + 3);
console.log(pm.variables.get('count'));

What will be printed in the console?

medium

A. 8

B. 5

C. Error: Cannot add number to undefined

D. null

Solution

1. Step 1: Set initial local variable 'count'

   The first line sets 'count' to 5.

2. Step 2: Increment 'count' by 3

   The second line gets 'count' (5), adds 3, and sets it back to 8.

3. Step 3: Output the updated value

   The console.log prints the current value of 'count', which is 8.

4. Final Answer:

   8 -> Option A

5. Quick Check:

   5 + 3 = 8 [OK]

Hint: Get then set to update local variable value [OK]

Common Mistakes:

• Assuming the variable does not update
• Expecting an error due to type mismatch
• Confusing local with environment variables

4. You wrote this Postman script:

pm.variables.set('user', 'Alice');
console.log(pm.variables.get('username'));

What is the problem here?

medium

A. Variable 'username' was never set, so get returns undefined

B. Syntax error in pm.variables.set method

C. Local variables cannot be logged to console

D. pm.variables.get requires two arguments

Solution

1. Step 1: Check variable names used

   The script sets 'user' but tries to get 'username', which was never set.

2. Step 2: Understand get behavior for unset variables

   Getting an unset local variable returns undefined, no error occurs.

3. Final Answer:

   Variable 'username' was never set, so get returns undefined -> Option A

4. Quick Check:

   Unset variable get = undefined [OK]

Hint: Check variable names carefully for typos [OK]

Common Mistakes:

• Assuming syntax error when variable name mismatches
• Thinking pm.variables.get needs two arguments
• Believing console.log cannot show local variables

5. You want to store a temporary token during a request and use it in multiple tests within that request. Which approach correctly uses local variables to achieve this?

hard

A. Set the token with pm.environment.set('token', 'abc') and get it with pm.variables.get('token')

B. Set the token once with pm.variables.set('token', 'abc') and get it in tests with pm.variables.get('token')

C. Set the token with pm.variables.set('token', 'abc') but cannot access it in other tests

D. Set the token with pm.globals.set('token', 'abc') and get it with pm.variables.get('token')

Solution

1. Step 1: Understand local variable scope within one request

   Local variables set with pm.variables.set are accessible throughout the request execution, including multiple tests.

2. Step 2: Verify correct get method usage

   Use pm.variables.get to retrieve the local variable value within the same request.

3. Step 3: Check other options for scope mismatch

   Environment and global variables persist beyond one request and are not local. Also, local variables are accessible across tests in the same request.

4. Final Answer:

   Set the token once with pm.variables.set('token', 'abc') and get it in tests with pm.variables.get('token') -> Option B

5. Quick Check:

   Local variable set/get works within one request [OK]

Hint: Use pm.variables.set/get to share data within one request [OK]

Common Mistakes:

• Using environment or global variables instead of local
• Thinking local variables cannot be shared between tests in one request
• Mixing set and get methods from different scopes