Closes https://github.com/microsoft/playwright/issues/32853
Vite turns the shorthand fragment notation `<></>` into `import {
Fragment } from "react"; <Fragment></Fragment>`. On the Node.js side of
things, this `react` import resolves to our mock version of React, which
currently mocks `Fragment` as `{}`. Currently, we pass that straight to
`React.createElement`, which throws an error.
The fix is to make our `Fragment` mock detectable with a tag, and when
we render it replace it with the real `__pwReact.Fragment`.
What was happening?
- When we use CT, we go over the test files, look at the imports using
`tsxTransform.ts` and store them inside a map, these we feed into the
import registry which we build using Vite and have access inside the
browser
- In case of an inline component in the same file as where the test file
is, this is not happening.
- jsx-runtime via babel kicks in, transforms every JSX component in
something like that:
```
{
__pw_type: 'jsx',
type: [Function: MyInlineComponent],
props: { value: 'Max' },
key: undefined
}
```
this then gets passed into `wrapObject` which maps any function from the
Node.js side into expose function calls so they work inside the browser.
The assumption for `wrapObject` was to do it mostly for callbacks. So it
does for `type` - which is actually our component. We then pass this to
the React render function, which calls back the exposed function but we
never return anything, so it mounts `undefined`.
---
While there have been experiments from certain vendors to get the
'client only' code inside a server side file, we should throw for now to
not confuse users. We might revisit this in the future since Babel / TSX
doesn't support it outside of the box.
Fixes https://github.com/microsoft/playwright/issues/32167
Closes https://github.com/microsoft/playwright/issues/32159. I
originally set out to enable Strict Mode for our React UI, but found a
way better thing: Enabling the lint rules we had already installed!
`eslint-plugin-react` is already in of our `package.json`, and this PR
enables it and fixes some of the reported issues. Most of them are
around the `key` prop which is mostly about performance, but there's
also fixes for misspelled `data-testid` props.
BREAKING CHANGE: Drop support for React 17 and earlier
Support for React 17 an earlier is provided by
`@playwright/experimental-ct-react-17`
Closes#19923
Currently, we ues `#root` vs `#root > *` selector for component roots
depending on the number of root children. This heuristic detects
fragments that render multiple elements inside the root.
However, this does not work with empty fragments that do not render
anything.
The fix is to make the `#root >> control=component` selector that would
dynamically detect the root. This supports empty fragments and also
allows for dynamic updates of the fragments.
