Variable assignment in flows in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Variable assignment in Postman pre-request script

What will be the value of the environment variable token after running this pre-request script in Postman?

Postman

pm.environment.set('token', 'initial');
if (pm.response && pm.response.code === 200) {
  pm.environment.set('token', 'updated');
} else {
  pm.environment.set('token', 'failed');
}

A "failed"

B "initial"

C "updated"

D undefined

💡 Hint

Remember that pre-request scripts run before the request is sent, so pm.response is not yet available.

In a pre-request script, pm.response is undefined because the request has not been sent yet. Therefore, the if condition is false, and the variable token is set to "failed".

❓ assertion

intermediate

Correct assertion for variable assignment in Postman test script

Which assertion correctly verifies that the global variable userId has been assigned the value 12345 in a Postman test script?

A pm.test('userId is 12345', () => pm.globals.get('userId') === '12345');

B pm.test('userId is 12345', () => pm.expect(pm.globals.get('userId')).to.eql('12345'));

C pm.test('userId is 12345', () => pm.globals.userId === 12345);

D pm.test('userId is 12345', () => pm.expect(pm.globals.userId).to.equal(12345));

💡 Hint

Use pm.expect with pm.globals.get() to access global variables properly.

Option B uses pm.expect to assert that the global variable userId (accessed via pm.globals.get('userId')) equals the string '12345'. This is the correct way to assert variable values in Postman test scripts.

🔧 Debug

advanced

Debugging variable assignment in Postman flow

Given this Postman test script, why does the variable sessionId remain undefined after the request?

Postman

if (pm.response.code === 200) {
  pm.variables.set('sessionId', pm.response.json().session);
}
console.log(pm.variables.get('sessionId'));

A Because <code>pm.variables.set</code> requires a third argument to persist the variable.

B Because <code>pm.response.code</code> is undefined in test scripts.

C Because <code>pm.response.json()</code> is not a valid method to parse JSON response.

D Because <code>pm.variables</code> only stores variables for the current request and is not persisted between requests.

💡 Hint

Consider the scope and lifetime of pm.variables compared to environment or global variables.

pm.variables stores variables only for the current request execution and does not persist them between requests. To keep sessionId for later requests, use pm.environment.set or pm.globals.set.

🧠 Conceptual

advanced

Understanding variable scopes in Postman flows

Which statement correctly describes the difference between pm.variables, pm.environment, and pm.globals in Postman?

A <code>pm.variables</code> are temporary for the current request, <code>pm.environment</code> variables persist per environment, and <code>pm.globals</code> persist globally across all environments.

B <code>pm.variables</code> persist globally, <code>pm.environment</code> are temporary, and <code>pm.globals</code> persist per environment.

C <code>pm.variables</code> and <code>pm.environment</code> are the same, but <code>pm.globals</code> are temporary.

D <code>pm.variables</code> persist per environment, <code>pm.environment</code> persist globally, and <code>pm.globals</code> are temporary.

💡 Hint

Think about how long each variable type lasts and where it is accessible.

pm.variables exist only during the current request execution and are not saved. pm.environment variables are saved per environment and persist across requests. pm.globals variables are saved globally and accessible in all environments.

❓ framework

expert

Postman flow variable assignment and test execution order

In a Postman collection run, which sequence correctly describes when variables are assigned and accessible during the flow?

A Variables set in pre-request scripts are only available after the entire collection run finishes; test scripts run before pre-request scripts.

B Test scripts run before the request; then pre-request scripts run; then the request is sent; variables set in test scripts are not saved.

C Pre-request scripts run first and can set variables; then the request is sent; then test scripts run and can update variables; environment and global variables persist between requests.

D Requests run first; then pre-request scripts run; then test scripts run; variables set in pre-request scripts are not accessible in test scripts.

💡 Hint

Recall the order of execution in Postman: pre-request script, request, test script.

Postman executes pre-request scripts before sending the request, allowing variable assignment before the request. After the request, test scripts run and can update variables. Environment and global variables persist between requests and across the collection run.