Setting variables in scripts in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the value of the environment variable after this script runs?

Consider this Postman test script that sets an environment variable. What will be the value of the environment variable userId after execution?

Postman

pm.environment.set('userId', 12345);
pm.environment.set('userId', Number(pm.environment.get('userId')) + 5);

A undefined

B Error: Cannot add number to undefined

C 12350

D 12345

💡 Hint

Remember that environment variables are stored as strings and you may need to convert them to numbers before arithmetic.

The script first sets the 'userId' environment variable to 12345. Then it retrieves the value (stored as string '12345'), converts it to a number using Number(), adds 5, and sets the variable to the result: 12350.

❓ assertion

intermediate

Which assertion correctly verifies a global variable value in Postman?

You want to check if the global variable token equals abc123 in a test script. Which assertion is correct?

A pm.test('Token is correct', () => pm.expect(pm.variables.get('token')).to.eql('abc123'));

B pm.test('Token is correct', () => pm.expect(pm.globals.get('token')).to.eql('abc123'));

C pm.test('Token is correct', () => pm.expect(pm.environment.get('token')).to.eql('abc123'));

D pm.test('Token is correct', () => pm.expect(pm.collectionVariables.get('token')).to.eql('abc123'));

💡 Hint

Global variables are accessed via pm.globals.get()

Global variables in Postman are accessed using pm.globals.get(). Using pm.environment.get() accesses environment variables, which is different.

🔧 Debug

advanced

Why does this script fail to set the collection variable?

This Postman script tries to set a collection variable but it does not appear in the collection variables list after running. What is the issue?

Postman

pm.collectionVariables.set('sessionId', 7890);
console.log('Session ID set to:', pm.collectionVariables.get('sessionId'));

A The collection variable is set but changes are not saved persistently until the collection is saved manually.

B Collection variables cannot be set dynamically in scripts; they must be set manually.

C The script runs in the wrong context; collection variables can only be set in pre-request scripts, not test scripts.

D The variable name 'sessionId' is reserved and cannot be used for collection variables.

💡 Hint

Check how Postman handles collection variable persistence after setting them in scripts.

Postman allows setting collection variables dynamically, but these changes are only saved in memory during the run. To persist changes, the collection must be saved manually after the run.

🧠 Conceptual

advanced

Which variable scope has the highest priority when accessing variables in Postman scripts?

In Postman scripts, variables can exist in multiple scopes: global, collection, environment, and local. Which scope is checked first when accessing a variable by name?

A Local variables

B Global variables

C Environment variables

D Collection variables

💡 Hint

Think about the closest scope to the script execution context.

Local variables have the highest priority because they are defined within the script and override other scopes. Then environment, collection, and global follow in that order.

❓ framework

expert

Which Postman script snippet correctly sets a variable only if it does not already exist?

You want to set an environment variable userRole to admin only if it is not already set. Which script snippet achieves this correctly?

A if (pm.environment.get('userRole') === '') { pm.environment.set('userRole', 'admin'); }

B if (pm.environment.get('userRole') === undefined) { pm.environment.set('userRole', 'admin'); }

C if (pm.environment.get('userRole') == null) { pm.environment.set('userRole', 'admin'); }

D if (!pm.environment.get('userRole')) { pm.environment.set('userRole', 'admin'); }

💡 Hint

Check how Postman returns undefined or null for unset variables and how JavaScript treats falsy values.

pm.environment.get() returns undefined if the variable is not set. The condition !pm.environment.get('userRole') checks for undefined, null, empty string, or other falsy values, so it safely sets the variable only if not set or empty.