From b82773cef7fc69349a55faf3b79eabc1e4ba4eeb Mon Sep 17 00:00:00 2001
From: Sebastian Silbermann <silbermann.sebastian@gmail.com>
Date: Wed, 15 Jul 2020 14:49:28 +0200
Subject: [PATCH] fix(unmount): Flush useEffect cleanup functions syncronously
 (#746)

---
 src/__tests__/render.js | 14 ++++++++++++++
 src/pure.js             |  6 +++++-
 2 files changed, 19 insertions(+), 1 deletion(-)

diff --git a/src/__tests__/render.js b/src/__tests__/render.js
index 54916ba4..4e78afa6 100644
--- a/src/__tests__/render.js
+++ b/src/__tests__/render.js
@@ -87,3 +87,17 @@ test('renders options.wrapper around node', () => {
 </div>
 `)
 })
+
+test('flushes useEffect cleanup functions sync on unmount()', () => {
+  const spy = jest.fn()
+  function Component() {
+    React.useEffect(() => spy, [])
+    return null
+  }
+  const {unmount} = render(<Component />)
+  expect(spy).toHaveBeenCalledTimes(0)
+
+  unmount()
+
+  expect(spy).toHaveBeenCalledTimes(1)
+})
diff --git a/src/pure.js b/src/pure.js
index be0fa3f1..f2f3438f 100644
--- a/src/pure.js
+++ b/src/pure.js
@@ -74,7 +74,11 @@ function render(
           el.forEach(e => console.log(prettyDOM(e, maxLength, options)))
         : // eslint-disable-next-line no-console,
           console.log(prettyDOM(el, maxLength, options)),
-    unmount: () => ReactDOM.unmountComponentAtNode(container),
+    unmount: () => {
+      act(() => {
+        ReactDOM.unmountComponentAtNode(container)
+      })
+    },
     rerender: rerenderUi => {
       render(wrapUiIfNeeded(rerenderUi), {container, baseElement})
       // Intentionally do not return anything to avoid unnecessarily complicating the API.