Jest: How to Run a Single Test (Step-by-Step Guide)

If you're using Jest for testing your JavaScript or TypeScript applications, you might often find yourself needing to run a single test instead of the entire test suite. This is especially useful when debugging or iterating quickly during development. In this article, we’ll show you how to run a single test in Jest with practical examples.

✅ Why Run a Single Test in Jest?

Running only one test can:

• Save time during development
• Make debugging easier
• Help isolate and resolve failing tests faster
• Improve focus on a specific feature or component

🔧 How to Run a Single Test in Jest

Jest offers multiple ways to run a specific test, depending on your needs.

1. Use .only on test or it

This is the easiest and most common way.

test.only('should return true for valid input', () => {
  expect(myFunction('valid')).toBe(true);
});

This tells Jest to only run this test and skip all others in the file.

You can also use it.only():

it.only('should do something specific', () => {
  expect(1 + 1).toBe(2);
});

👉 Don’t forget to remove .only before committing your code!

2. Run a Single Test File via CLI

You can run a specific test file using the command line:

npx jest path/to/file.test.js

Example:

npx jest tests/login.test.js

This will run all tests inside the login.test.js file.

3. Use -t or --testNamePattern to Match Test Names

If you want to run a specific test case within a file, use the -t flag:

npx jest -t 'should return true for valid input'

This works great when you know the name of the test. Jest will run all tests that match the provided pattern.

You can combine this with a specific file:

npx jest login.test.js -t 'valid login'

4. Use VS Code or Other IDE Shortcuts

If you’re using Visual Studio Code with the Jest extension, you can:

• Click the “Run” icon next to a test
• See results inline without leaving your editor

It’s a great productivity booster!

🧠 Pro Tip: Watch Mode for Quick Feedback

Enable Jest’s watch mode for faster iteration:

npx jest --watch

Now when you modify a file or test, Jest will automatically re-run related tests. You can also filter by file or test name interactively.

✅ Summary

🔍 Final Thoughts

Knowing how to run a single test in Jest is a simple yet powerful trick that can save you tons of time. Whether you're debugging a flaky test or focused on a new feature, using .only, -t, or running specific files can streamline your development workflow.