Environment variables in Postman - Framework Patterns

Framework Mode - Environment variables

Folder Structure for Postman Environment Variables

postman-project/
├── collections/
│   └── my-api-collection.json
├── environments/
│   ├── dev.postman_environment.json
│   ├── staging.postman_environment.json
│   └── prod.postman_environment.json
├── tests/
│   └── test-scripts.js
├── globals.postman_environment.json
└── README.md
  

Test Framework Layers in Postman with Environment Variables

• Collections: Group of API requests to test different endpoints.
• Environments: JSON files holding variables like base URLs, tokens, credentials for different setups (dev, staging, prod).
• Globals: Variables accessible across all environments and collections.
• Tests: Scripts written in JavaScript inside requests to validate responses using environment variables.
• Utilities: Scripts or pre-request scripts to set or update environment variables dynamically.

Configuration Patterns for Environment Variables in Postman

• Separate Environment Files: Maintain separate JSON files for each environment (dev, staging, prod) with relevant variables.
• Use Variable Scopes: Use environment variables for environment-specific data and global variables for common data.
• Secure Sensitive Data: Store sensitive info like API keys in environment variables, not hardcoded in requests.
• Dynamic Variable Updates: Use pre-request or test scripts to update environment variables during test runs.
• Environment Selection: Select the appropriate environment in Postman UI or via CLI (Newman) when running tests.

Test Reporting and CI/CD Integration

• Newman CLI: Run Postman collections with selected environment files and generate reports in formats like JSON, HTML.
• CI/CD Pipelines: Integrate Newman commands in pipelines (GitHub Actions, Jenkins) specifying environment files for automated testing.
• Report Analysis: Use generated reports to track pass/fail status of API tests per environment.
• Environment Variable Management: Use secure storage or secrets management in CI/CD to inject environment variables safely.

Best Practices for Using Environment Variables in Postman Frameworks

1. Keep Environment Files Separate: Avoid mixing variables for different environments to prevent accidental misuse.
2. Use Descriptive Variable Names: Make variable names clear and consistent for easy understanding.
3. Never Hardcode Sensitive Data: Always use environment variables for tokens, passwords, and keys.
4. Update Variables Dynamically: Use scripts to refresh tokens or update variables during test execution.
5. Version Control Environment Files Carefully: Exclude sensitive environment files from public repos or use encrypted storage.

Self Check Question

Where in this folder structure would you add a new environment variable for the staging environment?

Key Result

Use separate environment JSON files to manage variables for different setups, enabling flexible and secure API testing in Postman.

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