I’ve been thinking a lot about testing lately. Specifically, about the quiet frustration that comes when a test fails not because something is broken for the user, but because a developer changed a class name or refactored an internal state. It’s a common pain point in modern web development. This frustration is precisely why I want to talk about bringing two tools together: Jest and Testing Library. This isn’t just about checking boxes; it’s about building confidence that your application works for the people who matter most—your users. Let’s get into how this combination changes the game.
Think of Jest as the solid foundation. It’s the test runner, the assertion library, and the coverage reporter all in one. It sets up the environment, executes your code, and tells you what passed or failed. But on its own, Jest doesn’t dictate how you should test your components. You could write tests that are tightly coupled to your component’s internal structure. This is where Testing Library comes in. Its philosophy is simple: test your components the way a user would find and use them.
Why does this perspective shift matter so much? A user doesn’t know about your component’s state variable named isLoading; they see a spinner and a disabled button. A user doesn’t care about your data-cy test ID; they look for a button that says “Submit.” Testing Library provides queries that mirror this reality. You find elements by their role, by the text they display, or by their label. This approach has a wonderful side effect: it naturally encourages you to build more accessible applications. If you can’t find a button by its accessible role, maybe your button isn’t accessible.
So, how do they work together? Jest provides the stage, and Testing Library provides the script that focuses on user behavior. You write your tests in Jest’s familiar describe and it blocks, but you use Testing Library’s render and screen to interact with your component. The result is a test that is resilient to refactoring. Change your CSS-in-JS solution or switch from a div to a section? If the user’s experience is the same, your test should still pass.
Let’s look at a practical example. Imagine a simple login form. A test that only cares about implementation might check if a specific CSS class exists. A test written with our combined approach looks for what the user sees and does.
import { render, screen, fireEvent } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import LoginForm from './LoginForm';
describe('LoginForm', () => {
it('allows a user to log in successfully', async () => {
// Render the component
render(<LoginForm />);
// Find the inputs and button the way a user would
const emailInput = screen.getByRole('textbox', { name: /email/i });
const passwordInput = screen.getByLabelText(/password/i);
const submitButton = screen.getByRole('button', { name: /sign in/i });
// Simulate user typing - userEvent is closer to real browser behavior
await userEvent.type(emailInput, '[email protected]');
await userEvent.type(passwordInput, 'securepassword123');
// Simulate user clicking the button
await userEvent.click(submitButton);
// Assert on the outcome the user would experience
expect(await screen.findByText('Welcome back!')).toBeInTheDocument();
});
});Notice what we’re not doing. We’re not checking internal state. We’re not looking for a specific HTML element like a div. We’re describing a user’s journey: find the fields, type into them, click the button, and see a welcome message. This test will survive countless internal changes to the LoginForm component.
What about mocking? Jest’s powerful mocking system is fully compatible with this approach. You mock the external world—like a network request—so you can test how your component behaves in specific scenarios. The key is to still make assertions based on the resulting UI, not the mock call itself.
// Mock a module that handles an API call
import { loginUser } from '../api';
jest.mock('../api');
it('shows an error message on login failure', async () => {
// Tell the mock to reject
loginUser.mockRejectedValueOnce(new Error('Invalid credentials'));
render(<LoginForm />);
await userEvent.click(screen.getByRole('button', { name: /sign in/i }));
// Assert that the user sees an error, not that the mock was called
expect(await screen.findByText(/invalid email or password/i)).toBeInTheDocument();
});This is powerful. You’re simulating a real-world failure and confirming your component handles it gracefully from the user’s point of view. Have you considered how many bugs are caught simply by asking, “What does the user see now?”
The benefits extend to team dynamics and long-term maintenance. When tests are based on user behavior, they become a form of living documentation. A new developer can read a test file and quickly understand what a component is supposed to do. Furthermore, these tests tend to be more stable. They fail for meaningful reasons—because a feature is actually broken—not because of superficial changes. This saves hours of test maintenance and increases trust in your test suite.
Some developers initially worry that querying by role or text is less precise or slower. In practice, the Testing Library ecosystem provides a rich set of queries (getBy, findBy, queryBy) that allow for precise and efficient testing. The slight initial learning curve pays for itself many times over in test stability and clarity.
Integrating these tools into a React, Vue, or Svelte project is straightforward. After installing the packages, you configure Jest (usually via jest.config.js) and then write your tests focusing on the render and screen utilities from Testing Library. The mindset shift—from testing implementation to testing behavior—is the most critical part of the setup.
In the end, combining Jest and Testing Library is about aligning your testing efforts with your ultimate goal: creating a reliable, user-friendly application. It moves testing from being a chore that verifies code to a practice that verifies experience. It ensures that when all your tests pass, you can be confident that your application isn’t just technically correct—it’s ready for real people to use.
This approach has fundamentally changed how I build software, making deployments less stressful and development more focused. If this perspective on testing resonates with you, or if you have your own experiences to share, I’d love to hear from you. Let’s continue the conversation—drop a comment below, and if you found this useful, please share it with your team.
As a best-selling author, I invite you to explore my books on Amazon. Don’t forget to follow me on Medium and show your support. Thank you! Your support means the world!
101 Books
101 Books is an AI-driven publishing company co-founded by author Aarav Joshi. By leveraging advanced AI technology, we keep our publishing costs incredibly low—some books are priced as low as $4—making quality knowledge accessible to everyone.
Check out our book Golang Clean Code available on Amazon.
Stay tuned for updates and exciting news. When shopping for books, search for Aarav Joshi to find more of our titles. Use the provided link to enjoy special discounts!
📘 Checkout my latest ebook for free on my channel!
Be sure to like, share, comment, and subscribe to the channel!
Our Creations
Be sure to check out our creations:
Investor Central | Investor Central Spanish | Investor Central German | Smart Living | Epochs & Echoes | Puzzling Mysteries | Hindutva | Elite Dev | JS Schools
We are on Medium
Tech Koala Insights | Epochs & Echoes World | Investor Central Medium | Puzzling Mysteries Medium | Science & Epochs Medium | Modern Hindutva
