When developing UI components for web applications, it is crucial to ensure their correctness and maintain the expected behavior as the codebase evolves. Automated testing plays a significant role in achieving this and helps to catch potential bugs early in the development process.

One popular tool used for testing UI components is Storybook, which allows developers to showcase and explore various states of their components in isolation. With the addition of Storyshots, a Storybook addon, it becomes easy to generate snapshot tests for all your UI stories using different testing libraries.

What are snapshot tests?

Snapshot tests are a type of test that captures the rendered output of a component and stores it as a reference snapshot. Any subsequent runs of the test will compare the current output against the reference snapshot to ensure consistency. If the output differs from the snapshot, it indicates that the component has changed and requires a manual review.

Setting up Storyshots

To get started with Storyshots, you need to have a Storybook project up and running. If you haven’t set up Storybook yet, you can follow the official Storybook documentation to get started.

Once your Storybook project is set up, you can install Storyshots by running the following command:

npm install --save-dev @storybook/addon-storyshots

Writing Storyshots

To write snapshot tests for all the stories in your Storybook, you need to create a test file that utilizes the Storyshots addon. Here’s an example test file using Jest as the testing framework:

import initStoryshots from '@storybook/addon-storyshots';

initStoryshots();

The initStoryshots function initializes Storyshots and generates snapshot tests for all the stories in your Storybook project. By default, the snapshots will be stored under a folder named __snapshots__ in each of your story files.

Running Storyshots

You can now run the Storyshots test by executing the following command:

npm test

This will trigger Jest to run the snapshot tests and compare the rendered output of your components against the reference snapshots. If any inconsistencies are found, Jest will fail the test and provide details on what has changed.

Conclusion

Testing components in Storyshots for JavaScript Storybook provides an automated way to ensure the integrity of your UI components. It allows you to catch visual regressions and guarantees the expected behavior throughout the development process. By incorporating Storyshots into your testing workflow, you can save time and effort in manually testing each component and focus on building robust and reliable UI components.

#testing #storybook