fix: flush pending hooks effects in rerender

src/__tests__/rerender.js

@@ -1,5 +1,6 @@
 import '@testing-library/jest-dom/extend-expect'
 import { h } from 'preact'
+import { useState, useEffect } from 'preact/hooks'
 import { render } from '..'
 
 test('rerender will re-render the element', () => {
@@ -12,6 +13,23 @@ test('rerender will re-render the element', () => {
   expect(container.firstChild).toHaveTextContent('hey')
 })
 
+test('rerender will flush pending hooks effects', async () => {
+  const Component = () => {
+    const [value, setValue] = useState(0)
+    useEffect(() => {
+      const timeoutId = setTimeout(() => setValue(1), 0)
+      return () => clearTimeout(timeoutId)
+    })
+
+    return value
+  }
+
+  const { rerender, findByText } = render(<Component />)
+  rerender(<Component />)
+
+  await findByText('1')
+})
+
 test('hydrate will not update props until next render', () => {
   const initialInputElement = document.createElement('input')
   const container = document.createElement('div')

src/pure.js

@@ -69,7 +69,7 @@ function render (
         : console.log(prettyDOM(el, maxLength, options)),
     unmount: () => preactRender(null, container),
     rerender: (rerenderUi) => {
-      setupRerender()()
+      act(() => {})
       render(wrapUiIfNeeded(rerenderUi), { container, baseElement })
       // Intentionally do not return anything to avoid unnecessarily complicating the API.
       // folks can use all the same utilities we return in the first place that are bound to