From e25e27eca831432cebf457f1910fae1c02ae52e7 Mon Sep 17 00:00:00 2001
From: Imre Osswald <ioss@users.noreply.github.com>
Date: Fri, 30 Nov 2018 16:02:19 +0100
Subject: [PATCH] Fix bug in cloneHook (#14364)

* Fixes #14360 and adds a test for mixed priority dispatches.

It was broken because `cloneHook` assigned `memoizedState` instead of
`baseState` from the original hook to `baseState` of the clone.

* tweak comments
---
 .../react-reconciler/src/ReactFiberHooks.js   |  2 +-
 ...eactHooksWithNoopRenderer-test.internal.js | 33 +++++++++++++++++++
 2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/packages/react-reconciler/src/ReactFiberHooks.js b/packages/react-reconciler/src/ReactFiberHooks.js
index 3d6de1be19777..5122a8dda4a0e 100644
--- a/packages/react-reconciler/src/ReactFiberHooks.js
+++ b/packages/react-reconciler/src/ReactFiberHooks.js
@@ -253,7 +253,7 @@ function cloneHook(hook: Hook): Hook {
   return {
     memoizedState: hook.memoizedState,
 
-    baseState: hook.memoizedState,
+    baseState: hook.baseState,
     queue: hook.queue,
     baseUpdate: hook.baseUpdate,
 
diff --git a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js
index 36030a2124390..ea5672147464c 100644
--- a/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.internal.js
@@ -565,6 +565,39 @@ describe('ReactHooksWithNoopRenderer', () => {
       ReactNoop.flush();
       expect(ReactNoop.getChildren()).toEqual([span('Count: 8')]);
     });
+
+    // Regression test for https://github.com/facebook/react/issues/14360
+    it('handles dispatches with mixed priorities', () => {
+      const INCREMENT = 'INCREMENT';
+
+      function reducer(state, action) {
+        return action === INCREMENT ? state + 1 : state;
+      }
+
+      function Counter(props, ref) {
+        const [count, dispatch] = useReducer(reducer, 0);
+        useImperativeMethods(ref, () => ({dispatch}));
+        return <Text text={'Count: ' + count} />;
+      }
+
+      Counter = forwardRef(Counter);
+      const counter = React.createRef(null);
+      ReactNoop.render(<Counter ref={counter} />);
+
+      ReactNoop.flush();
+      expect(ReactNoop.getChildren()).toEqual([span('Count: 0')]);
+
+      counter.current.dispatch(INCREMENT);
+      counter.current.dispatch(INCREMENT);
+      counter.current.dispatch(INCREMENT);
+      ReactNoop.flushSync(() => {
+        counter.current.dispatch(INCREMENT);
+      });
+      expect(ReactNoop.getChildren()).toEqual([span('Count: 1')]);
+
+      ReactNoop.flush();
+      expect(ReactNoop.getChildren()).toEqual([span('Count: 4')]);
+    });
   });
 
   describe('useEffect', () => {