Stories in unit tests
Teams test a variety of UI characteristics using different tools. Each tool requires you to replicate the same component state over and over. That’s a maintenance headache. Ideally, you’d set up your tests similarly and reuse that across tools.
Storybook enables you to isolate a component and capture its use cases in a *.stories.js|ts
file. Stories are standard JavaScript modules that are cross-compatible with the whole JavaScript ecosystem.
Stories are a practical starting point for UI testing. Import stories into tools like Jest, Testing Library, Vitest and Playwright, to save time and maintenance work.
Write a test with Testing Library
Testing Library is a suite of helper libraries for browser-based component tests. With Component Story Format, your stories are reusable with Testing Library. Each named export (story) is renderable within your testing setup. For example, if you were working on a login component and wanted to test the invalid credentials scenario, here's how you could write your test:
Storybook provides a composeStories
utility that helps convert stories from a test file into renderable elements that can be reused in your Node tests with JSDOM. It also allows you to apply other Storybook features that you have enabled your project (e.g., decorators, args) into your tests, enabling you to reuse your stories in your testing environment of choice (e.g., Jest, Vitest), ensuring your tests are always in sync with your stories without having to rewrite them. This is what we refer to as portable stories in Storybook.
You must configure your test environment to use portable stories to ensure your stories are composed with all aspects of your Storybook configuration, such as decorators.
Once the test runs, it loads the story and renders it. Testing Library then emulates the user's behavior and checks if the component state has been updated.
Override story properties
By default, the setProjectAnnotations
function injects into your existing tests any global configuration you've defined in your Storybook instance (i.e., parameters, decorators in the preview.js|ts
file). Nevertheless, this may cause unforeseen side effects for tests that are not intended to use these global configurations. For example, you may want to always test a story in a particular locale (via globalTypes
) or configure a story to apply specific decorators
or parameters
.
To avoid this, you can override the global configurations by extending either the composeStory
or composeStories
functions to provide test-specific configurations. For example:
Run tests on a single story
You can use the composeStory
function to allow your tests to run on a single story. However, if you're relying on this method, we recommend that you supply the story metadata (i.e., the default export) to the composeStory
function. This ensures that your tests can accurately determine the correct information about the story. For example:
Combine stories into a single test
If you intend to test multiple stories in a single test, use the composeStories
function. It will process every component story you've specified, including any args
or decorators
you've defined. For example:
Troubleshooting
Run tests in other frameworks
Storybook provides community-led addons for other frameworks like Vue 2 and Angular. However, these addons still lack support for the latest stable Storybook release. If you're interested in helping out, we recommend reaching out to the maintainers using the default communication channels (GitHub and Discord server).
The args are not being passed to the test
The components returned by composeStories
or composeStory
not only can be rendered as React components but also come with the combined properties from the story, meta, and global configuration. This means that if you want to access args or parameters, for instance, you can do so:
Learn about other UI tests
- Component tests for user behavior simulation
- Visual tests for appearance
- Accessibility tests for accessibility
- Snapshot tests for rendering errors and warnings
- Test runner to automate test execution
- Test coverage for measuring code coverage
- End-to-end tests for simulating real user scenarios
- Unit tests for functionality