A utility for shallow rendering React components in tests.
It's available on npm as render-shallow, so you can run:
npm install --save render-shallow
renderShallow shallow renders a React element, using React's ShallowRenderer test utility. It wraps the renderer creation, and returns the rendered component, along with some helpers to rerender the element, should it change.
// import renderShallow from 'render-shallow'// or:// const renderShallow = require('render-shallow')returns: Object output ReactElement rerender
The React element returned by the shallow renderer.
returns: React element
Function that gets the rendered output again. Useful for when a component's state has changed and the DOM should be updated.
Function that renders
newElement with the same render instance that
renderShallow used. If context was initially specified, that will be reused, otherwise you can supply it. Useful for when you want to tests a props update to your component.
returns: Element instance
Function that gets the mounted instance of the element. Useful if you want to check or use instance state or lifecycle methods.
// if you just want the shallow-renderer componentconst component = output// if you want to rerenderconst output rerender =// if you want to rerender the elementconst output rerenderElement =// if you want the component's instanceconst instance =
I found that in most of the React component tests I wrote, I simply wanted a shallow rendered component to test. The ShallowRenderer API is a little verbose, between the creation and the getting of the output. So I started abstracting that (the
.output returned from
renderShallow). When I found myself wanting to rerender the component, either because of state or props changes, I added the ability to both re-fetch the output (
rerender), or render the element again with new props (
rerenderElement). Some time later, when I wanted to test a lifecycle method not part of the shallow render lifecycle, I added
instance() so I could call the lifecycle hook directly on the element instance.
npm run compile- Builds a distributable version of the project
npm start- Runs tests and reruns on file change
npm test- Runs tests once