Stencil, a tool for building modern Web Components, has introduced a unit testing framework to enhance its capabilities. This framework focuses on simplicity and minimalism, offering two main methods: render() for rendering components and flush() for rerendering elements after changes. To begin unit testing Stencil components, users can clone the Stencil Component Starter and use npm commands to install necessary packages and run tests, with Jest as the testing tool. The setup involves configuring the project's package.json file, including defining testing scripts and configuring Jest to handle TypeScript and JSX files. The provided test file in the Stencil Component Starter demonstrates testing a component's build and rendering, using the render() and flush() functions for asynchronous manipulation of HTML elements. The article outlines the testing API, setup requirements, and includes a basic example test, with a promise of future posts exploring test-driven development and component extension.