Environment variables in Postman

Introduction

Environment variables help you store and reuse values like URLs or tokens easily. They make tests simpler and faster to update.

When you want to run the same test on different servers like development, testing, and production.

When you need to keep sensitive data like API keys safe and separate from your test scripts.

When you want to avoid repeating the same value in many places in your tests.

When you want to quickly change a value used in many requests without editing each one.

When you want to share common data across multiple requests or collections.

Syntax

Postman

pm.environment.set("variable_key", "value");
pm.environment.get("variable_key");
pm.environment.unset("variable_key");

Use pm.environment.set to create or update a variable.

Use pm.environment.get to read a variable's value.

Use pm.environment.unset to remove a variable.

Examples

Sets the environment variable baseUrl to the API URL.

Postman

pm.environment.set("baseUrl", "https://api.example.com");

Gets the value of the authToken variable to use in a request.

Postman

const token = pm.environment.get("authToken");

Removes the variable tempData from the environment.

Postman

pm.environment.unset("tempData");

Sample Program

This script sets an environment variable userId, retrieves it, prints it, and checks if it equals "12345".

Postman

// Set environment variable
pm.environment.set("userId", "12345");

// Get and print environment variable
const userId = pm.environment.get("userId");
console.log(`User ID is: ${userId}`);

// Use environment variable in a test
pm.test("User ID should be 12345", function () {
    pm.expect(userId).to.eql("12345");
});

Important Notes

Environment variables are case-sensitive.

Always clear variables you no longer need to avoid confusion.

You can manage environment variables in Postman's UI under the Environment quick look.

Summary

Environment variables store reusable values for your tests.

They help run tests easily on different setups without changing code.

Use Postman scripts to set, get, and remove these variables.

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