Environment variables are essential aspects of a project as they help simulate runtime conditions for code without changing the underlying script.
A codebase without environment variables would have hardcoded values that aren’t flexible and throw errors in different environments, such as testing, development, and production.
Overview
What is a Jest Environment Variable?
A Jest environment variable is used to provide dynamic inputs like API keys, database URLs, or environment settings without hardcoding them in test files.They are accessed using process.env and allow for flexible, reusable, and secure test setups.
Why Mock Jest Environment Variable?
Mocking Jest Environment Variable isolates dependencies, ensuring tests run reliably under different configurations without altering the .env file.
How to Mock Jest Environment Variable?
Use a global setup file (jest.setup.js) to load variables with require(‘dotenv‘).config() and access them via process.env.
In Jest, environment variables play crucial roles in security, maintainability, calling APIs, establishing database connections, and feature toggles.
What is Jest?
Jest is an open-source JavaScript-based testing framework that supports Angular, Vue, Node JS, React, Babel, TypeScript projects, and more. The primary purpose of implementing Jest is to ease the process of testing complex web applications. It works out-of-the-box for many front-end frameworks by significantly reducing the configuration time and complexities.
Jest extends its support to test any JavaScript-based codebase. Also, it doesn’t rely heavily on third-party applications, which makes it simpler and more handy. It is also a faster option when executing several test scripts.
What are Environment Variables?
Environment variables are predetermined values that are used to configure runtime behavior without having to change the codebase. In this way, you can change the value of the code application from outside the application. In Jest, environment variables help set up dynamic and flexible scenarios to mimic real-world situations.
One of the primary purposes of environmental variables is that they keep our code clean by externalizing configurational values instead of hardcoding them on our codebase.
Moreover, this allows the code to be more secure by hiding API keys and database credentials, which could be easily accessible otherwise.
Read More: Understanding Jest Parameterized Tests
Setting up Environment Variables in Jest
When executing Jest tests, a lot of situations make us rely upon environment variables to process further. Here is an efficient way to set up the environment variables in your Jest project.
Step 1. In the root directory of your project, create a new file with an extension “.env”.
Step 2. Collect all your environment variables and insert them in this file in the key-value format such as:
API_KEY=123456 NODE_ENV=test
Step 3. Launch the terminal in your project’s root folder, and enter the following command.
npm install dotenv --save-dev
The above command installs the .env configurations into your project, as they are not included by default with the Jest package.
These steps are useful in configuring the environment variables into your Jest tests.
Accessing Environment Variables in Jest
After configuring environment variables in your project, here’s how you can access them in your tests:
- Load Directly in the Test File: You can access environment variables directly within your test files.
- Use a Global Setup File (Recommended for Large Projects): For larger projects, it’s better to create a global setup file to store and manage all environment variables. This approach centralizes their management and makes them accessible wherever needed in your project using the following syntax.
require('dotenv').config();
test('example test', () => {
expect(process.env.API_KEY).toBe('123456');
});How to mock Environment Variables with Jest?
Mocking is the process of replacing the real variable or function with an alternate one to stop relying upon external dependencies. Its purpose is to isolate the element so that any slight change with another factor doesn’t affect the element under test.
In testing, it is crucial yet useful to identify whether the code works properly under different configurations without modifying the ‘.env’ file.
1. Using a Global Setup file: Create a global setup file in your project, “jest.setup.js” to load all the environment variables simultaneously, adding the following script.
require('dotenv').config();Also, add the following configuration in your jest.configure.js file to use the above setup file.
module.exports = {
setupFiles: ['<rootDir>/jest.setup.js'],
};2. Accessing the environment variable: Once the variables are loaded, here’s how you can access them using “process.env”.
test('API key should be loaded from .env', () => {
expect(process.env.API_KEY).toBe('123456');
});Common Challenges with Jest Environment Variables
Jest Environment Variables streamline the entire testing process for a Jest project, however, there are some common challenges one may come across while working with Environment variables in Jest.
- One may face the issues of environment variables not being loaded properly. This may occur due to incorrect configuration of ‘dotenv’ package. Jest doesn’t provide the ‘dotenv’ package by default therefore, it has to be installed using the Npm command and has to be imported into the test file.
- Test failures are also seen due to environmental variables missing or undefined. This occurs when they are not set up correctly in the environment. This issue can be fixed by setting up required Environment Variables at the beginning of the test or using the Global Variables and referencing them in the tests.
- A test may also fail when you have a single ‘.env’ file for all testing scenarios, which doesn’t accommodate multiple test environments. A quick way to resolve such an issue is by creating multiple ‘.env’ files like .env.test, .env.staging, etc., and loading them as needed.
Read More: How to Configure Jest
Running Jest Tests across Different Environments
Testing across different environments is a crucial step as it ensures the robustness of our application in different scenarios and also tests it under real user conditions, thus resulting in broader coverage.
Alongside such pros, there are certain challenges during test execution across different environments, such as different environments seeking different setups, different behavior in different operating systems, network issues in fetching APIs, and much more.
BrowserStack Automate is the one-stop solution to tackle all those challenges with ease. It provides features such as Parallel testing where one can test their application across numerous device and operating system combinations at once without relying upon physical devices.
Here’s how you can run tests using Jest on BrowserStack’s Selenium Grid:
Step 1: Pick any project of your choice or clone a sample project using the following command.
git clone https://github.com/browserstack/jest-js-browserstack.git Cd jest-js-browserstack npm install
Step 2: Obtain your BrowserStack credentials from the BrowserStack Profile. Replace the username and accesskey obtained in the browserstack.yml file.
Step 3: The browserstack.yml file configures the device and browser combinations. Here’s the sample file you can use for your project, which has three parallel threads configured.
userName: #enter username here accessKey: #enter accesskey here platforms: - os: Windows osVersion: 10 browserName: Chrome browserVersion: 120.0 - os: OS X osVersion: Monterey browserName: Safari browserVersion: 15.6 - deviceName: iPhone 13 osVersion: 15 browserName: Chromium deviceOrientation: portrait parallelsPerPlatform: 1 browserstackLocal: true buildName: browserstack-build-1 projectName: BrowserStack Sample debug: false networkLogs: false consoleLogs: errors
Step 4: To run the test, use the following command from the root directory of your project.
npm run sample-test
Once the test is executed, you can view the results from the Automate dashboard.
Why run Jest Tests on Real Devices?
Testing is an essential part of the software development cycle. It assures that users receive the best product, sustaining the company’s reputation in the process. That said, testing on real devices ensures the ground-level performance of the application under test.
It provides accurate results and ensures the product is ready to roll out in the market to real-world users. However, setting up a lab full of devices is a very costly and time-consuming way to test on real devices.
BrowserStack offers cloud testing, where you can test your application on multiple devices on the cloud without physically having them. This saves an immense amount of capital and provides accurate reports. With seamless CI/CD integration and detailed reporting, BrowserStack ensures reliable, scalable, and efficient cross-browser testing in real-world conditions.
Conclusion
Environment variables are dynamic values that help configure test runtime conditions without changing the underlying code. This is a very useful aspect of software testing, as testing under different environments ensures the quality of code and the robustness of your application.
Environment variables’ primary purpose is to prevent the hardcoding of many runtime conditions. This flexibility increases efficiency and convenience in the testing environment.
Also, certain challenges occur while dealing with Environment Variables, such as different environments seeking different setups, different behavior in different operating systems, network issues in fetching APIs, and much more. With the help of BrowserStack Automate, all these challenges are easily overcome with added benefits.
Featured Article
