Environment variables in Postman - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of Environment Variables in Postman

What is the main purpose of using environment variables in Postman?

A To store values that can change between different environments like development, testing, and production

B To write JavaScript code that runs before sending a request

C To create collections of API requests for sharing

D To generate random data for testing

💡 Hint

Think about how you can reuse the same request with different settings.

Environment variables allow you to store values that differ between environments, such as URLs or API keys, so you can switch easily without changing each request.

❓ Predict Output

intermediate

Output of Accessing Environment Variable in Test Script

What will be the output of the following Postman test script if the environment variable userId is set to 12345?

Postman

const userId = pm.environment.get('userId');
console.log(`User ID is: ${userId}`);
pm.test('Check userId', () => {
    pm.expect(userId).to.eql('12345');
});

A User ID is: 12345 (test passes)

B User ID is: undefined (test fails)

C User ID is: 12345 (test fails)

D SyntaxError due to incorrect pm.expect usage

💡 Hint

Check how pm.environment.get retrieves the variable and how the assertion compares values.

The environment variable userId is correctly retrieved and equals '12345', so the console logs the value and the test passes.

❓ locator

advanced

Correct Locator for Environment Variable in Postman Pre-request Script

Which of the following lines correctly sets an environment variable named token to the value abc123 in a Postman pre-request script?

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

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

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

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

💡 Hint

Remember environment variables are set with a specific Postman API method.

The correct method to set an environment variable is pm.environment.set. Other options set different scopes or are invalid.

❓ assertion

advanced

Assertion to Verify Environment Variable Exists and Is Not Empty

Which assertion correctly verifies that the environment variable sessionId exists and is not an empty string in a Postman test script?

Postman

const sessionId = pm.environment.get('sessionId');

A pm.expect(sessionId).to.equal(null);

B pm.expect(sessionId).to.exist.and.to.be.empty;

C pm.expect(sessionId).to.be.undefined;

D pm.expect(sessionId).to.be.a('string').and.not.empty;

💡 Hint

Check how to assert a string is not empty and exists.

Option D checks that sessionId is a string and is not empty, which confirms it exists and has a value.

🔧 Debug

expert

Debugging Environment Variable Not Updating in Postman

You have this test script in Postman:

pm.environment.set('count', 1);
let count = pm.environment.get('count');
count++;
pm.environment.set('count', count);
console.log('Count is:', count);

After running the request multiple times, the count variable always logs 2. What is the most likely reason?

A Postman does not allow updating environment variables in test scripts

B The environment variable <code>count</code> is being reset to 1 every time before incrementing

C The <code>count++</code> operation does not change the variable value

D The console.log statement is incorrect and does not show updated value

💡 Hint

Look at the first line and how it affects the variable on each run.

The script sets count to 1 at the start every time, so incrementing always starts from 1, never accumulating.

Practice

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

easy

A. To store reusable values that can be used across multiple requests

B. To write test assertions for API responses

C. To create new API endpoints automatically

D. To generate random data for requests

Solution

1. Step 1: Understand environment variables role

   Environment variables hold values like URLs or tokens that you reuse in many requests.

2. Step 2: Compare with other options

   Writing tests or generating data are different features, not the main use of environment variables.

3. Final Answer:

   To store reusable values that can be used across multiple requests -> Option A

4. Quick Check:

   Environment variables = reusable values [OK]

Hint: Environment variables hold reusable data for requests [OK]

Common Mistakes:

• Confusing environment variables with test scripts
• Thinking environment variables create endpoints
• Assuming they generate random data automatically

2. Which of the following is the correct way to set an environment variable named token to abc123 in a Postman test script?

easy

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

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

C. pm.environment.get('token', 'abc123');

D. pm.setEnvironment('token', 'abc123');

Solution

1. Step 1: Identify correct method to set environment variable

   Postman uses pm.environment.set(key, value) to set environment variables.

2. Step 2: Check other options for correctness

   pm.variables.set sets local variables, pm.environment.get is for getting values, and pm.setEnvironment is not a valid method.

3. Final Answer:

   pm.environment.set('token', 'abc123'); -> Option A

4. Quick Check:

   Set env var = pm.environment.set(key, value) [OK]

Hint: Use pm.environment.set() to assign environment variables [OK]

Common Mistakes:

• Using pm.environment.get() to set variables
• Confusing pm.variables.set() with environment variables
• Using non-existent methods like pm.setEnvironment()

3. Given the following Postman test script, what will be the value of the environment variable userId after execution?

pm.environment.set('userId', 10);
pm.environment.set('userId', Number(pm.environment.get('userId')) + 5);

medium

A. Error

B. 10

C. undefined

D. 15

Solution

1. Step 1: Analyze first line setting userId

   The first line sets userId to 10.

2. Step 2: Analyze second line updating userId

   The second line gets current userId (10), adds 5, and sets it back, so userId becomes 15.

3. Final Answer:

   15 -> Option D

4. Quick Check:

   10 + 5 = 15 [OK]

Hint: Get then set adds values correctly [OK]

Common Mistakes:

• Assuming variable stays 10 after second line
• Thinking get returns undefined initially
• Expecting a runtime error

4. You wrote this Postman script to remove an environment variable sessionId but it does not work:

pm.environment.delete('sessionId');

What is the correct way to delete an environment variable?

medium

A. pm.environment.remove('sessionId');

B. pm.environment.unset('sessionId');

C. pm.environment.clear('sessionId');

D. pm.environment.deleteVariable('sessionId');

Solution

1. Step 1: Identify correct method to delete environment variable

   Postman uses pm.environment.unset(key) to remove environment variables.

2. Step 2: Check why original code fails

   pm.environment.delete() is not a valid method, so it does not remove the variable.

3. Final Answer:

   pm.environment.unset('sessionId'); -> Option B

4. Quick Check:

   Delete env var = pm.environment.unset(key) [OK]

Hint: Use pm.environment.unset() to remove variables [OK]

Common Mistakes:

• Using pm.environment.delete() which is invalid
• Trying pm.environment.remove() or clear() which don't exist for single variables
• Confusing with non-existent deleteVariable()

5. You want to run the same Postman collection on two different servers: dev and prod. Which is the best way to use environment variables to switch the base URL without changing the request code?

hard

A. Use global variables to store the URLs and change them before each run

B. Hardcode the server URL in each request and manually change it before running

C. Create two environments with a variable baseUrl set to each server URL, then select the environment before running

D. Write separate collections for dev and prod with different URLs

Solution

1. Step 1: Understand environment variables for different setups

   Creating separate environments with baseUrl variables allows easy switching without code changes.

2. Step 2: Compare other options

   Hardcoding or separate collections cause manual errors and duplication; global variables are less flexible for multiple setups.

3. Final Answer:

   Create two environments with a variable baseUrl set to each server URL, then select the environment before running -> Option C

4. Quick Check:

   Use environments to switch URLs easily [OK]

Hint: Use separate environments with baseUrl variables [OK]

Common Mistakes:

• Hardcoding URLs in requests
• Using global variables instead of environments
• Creating duplicate collections for each server