We can’t release software out into the wild without performing one of the most critical tasks – testing! There are two ways to do this with Svelte Web Components; we can run unit tests or bundle components into a package ready for testing in an environment such as a CodeSandBox demo. By now, we’ve already tested them in part when we hooked them into Storybook; this chapter will complete the process so that by the end, we should be confident that the components work as well as expected (at least in the confines of this book!)