Fix incorrect Transition boundary for Dialog component (#3331)

* always wrap `Dialog` in a `Transition`

Initially we didn't do this, because it's a bit silly to do that if you
already had a `Transition` component on the outside. E.g.:

```tsx
<Transition show={open}>
  <Dialog onClose={() => setOpen(false)}>
    {/* ... */}
  </Dialog>
</Transition>
```

Because this means that we technically have this:
```tsx
<Transition show={open}>
  <Dialog onClose={() => setOpen(false)}>
    <Transition>
      <InternalDialog>
        {/* ... */}
      </InternalDialog>
    </Dialog>
  </Transition>
</Transition>
```

The good part is that the inner `Transition` is rendering a `Fragment`
and forwards all the props to the underlying element (the internal
dialog).

This way we have a guaranteed transition boundary.

* use public `transition` API instead of private internal API

This also mimics better what we are actually trying to do.

* update changelog

packages/@headlessui-react/CHANGELOG.md

@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix issues spreading omitted props onto components ([#3313](https://github.com/tailwindlabs/headlessui/pull/3313))
 - Fix initial `anchor="selection"` positioning ([#3324](https://github.com/tailwindlabs/headlessui/pull/3324))
 - Fix render prop in `ComboboxOptions` to use `any` instead of `unknown` ([#3327](https://github.com/tailwindlabs/headlessui/pull/3327))
+- Fix incorrect `Transition` boundary for `Dialog` component ([#3331](https://github.com/tailwindlabs/headlessui/pull/3331))
 
 ## [2.1.0] - 2024-06-21
 

packages/@headlessui-react/src/components/dialog/dialog.test.tsx

@@ -1,21 +1,20 @@
 import { render } from '@testing-library/react'
-import React, { createElement, Fragment, useCallback, useEffect, useRef, useState } from 'react'
+import React, { Fragment, createElement, useCallback, useEffect, useRef, useState } from 'react'
 import { createPortal } from 'react-dom'
-import { OpenClosedProvider, State } from '../../internal/open-closed'
 import {
+  DialogState,
+  PopoverState,
   assertActiveElement,
   assertDialog,
   assertDialogDescription,
   assertDialogTitle,
   assertPopoverPanel,
-  DialogState,
   getByText,
   getDialog,
   getDialogs,
   getPopoverButton,
-  PopoverState,
 } from '../../test-utils/accessibility-assertions'
-import { click, focus, Keys, mouseDrag, press, shift } from '../../test-utils/interactions'
+import { Keys, click, focus, mouseDrag, press, shift } from '../../test-utils/interactions'
 import { suppressConsoleLogs } from '../../test-utils/suppress-console-logs'
 import type { PropsOf } from '../../types'
 import { Popover } from '../popover/popover'
@@ -498,25 +497,51 @@ describe('Rendering', () => {
     it(
       'should remove the scroll lock when the open closed state is `Closing`',
       suppressConsoleLogs(async () => {
-        function Example({ value = State.Open }) {
+        function Example({ open = true }) {
+          return (
+            <Dialog transition autoFocus={false} open={open} onClose={() => {}}>
+              <input id="a" type="text" />
+              <input id="b" type="text" />
+              <input id="c" type="text" />
+            </Dialog>
+          )
+        }
+
+        let { rerender } = render(<Example open={true} />)
+
+        // The overflow should be there
+        expect(document.documentElement.style.overflow).toBe('hidden')
+
+        // Re-render but with an exit transition
+        rerender(<Example open={false} />)
+
+        // The moment the dialog is closing, the overflow should be gone
+        expect(document.documentElement.style.overflow).toBe('')
+      })
+    )
+
+    it(
+      'should remove the scroll lock when the open closed state is `Closing` (using Transition wrapper)',
+      suppressConsoleLogs(async () => {
+        function Example({ open = true }) {
           return (
-            <OpenClosedProvider value={value}>
-              <Dialog autoFocus={false} open={true} onClose={() => {}}>
+            <Transition show={open}>
+              <Dialog autoFocus={false} onClose={() => {}}>
                 <input id="a" type="text" />
                 <input id="b" type="text" />
                 <input id="c" type="text" />
               </Dialog>
-            </OpenClosedProvider>
+            </Transition>
           )
         }
 
-        let { rerender } = render(<Example value={State.Open} />)
+        let { rerender } = render(<Example open={true} />)
 
         // The overflow should be there
         expect(document.documentElement.style.overflow).toBe('hidden')
 
-        // Re-render but with the `Closing` state
-        rerender(<Example value={State.Open | State.Closing} />)
+        // Re-render but with an exit transition
+        rerender(<Example open={false} />)
 
         // The moment the dialog is closing, the overflow should be gone
         expect(document.documentElement.style.overflow).toBe('')

packages/@headlessui-react/src/components/dialog/dialog.tsx

@@ -390,8 +390,7 @@ function DialogFn<TTag extends ElementType = typeof DEFAULT_DIALOG_TAG>(
     )
   }
 
-  let inTransitionComponent = usesOpenClosedState !== null
-  if (!inTransitionComponent && open !== undefined && !rest.static) {
+  if ((open !== undefined || transition) && !rest.static) {
     return (
       <Transition show={open} transition={transition} unmount={rest.unmount}>
         <InternalDialog ref={ref} {...rest} />