From 21159c6c7045453643ad43df0b8bfb605ddb411c Mon Sep 17 00:00:00 2001
From: MapleLeaf <19603573+itsMapleLeaf@users.noreply.github.com>
Date: Wed, 22 Dec 2021 20:51:15 -0600
Subject: [PATCH] cloneInstance fix: preserve children

---
 integration/rendering.test.tsx | 11 ++++++++---
 src/reconciler.ts              | 11 ++++++++++-
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/integration/rendering.test.tsx b/integration/rendering.test.tsx
index 058a1be..534d0e9 100644
--- a/integration/rendering.test.tsx
+++ b/integration/rendering.test.tsx
@@ -253,13 +253,18 @@ test("button onClick", async () => {
 test("button click with state", async () => {
   function Counter() {
     const [count, setCount] = useState(0)
-    return <Button onClick={() => setCount(count + 1)}>{count}</Button>
+    return (
+      <>
+        the count is {count}
+        <Button onClick={() => setCount(count + 1)}>increment</Button>
+      </>
+    )
   }
 
   async function assertCount(count: number) {
     await assertMessages([
       {
-        content: "_ _",
+        content: `the count is ${count}`,
         components: [
           {
             type: "ACTION_ROW",
@@ -267,7 +272,7 @@ test("button click with state", async () => {
               {
                 type: "BUTTON",
                 style: "SECONDARY",
-                label: String(count),
+                label: "increment",
                 disabled: false,
               },
             ],
diff --git a/src/reconciler.ts b/src/reconciler.ts
index cb592ed..13eb895 100644
--- a/src/reconciler.ts
+++ b/src/reconciler.ts
@@ -89,7 +89,16 @@ export const reconciler = ReactReconciler<
     type: ElementTag,
     oldProps: Props,
     newProps: Props,
-  ) => createInstance(type, newProps),
+  ) => {
+    const newInstance = createInstance(type, newProps)
+
+    // instance children don't get carried over, so we need to copy them
+    if ("children" in instance && "children" in newInstance) {
+      newInstance.children = instance.children
+    }
+
+    return newInstance
+  },
 
   // returning a non-null value tells react to re-render the whole thing
   // on any prop change