From 4c4f5fd27fc1d7c16033a1221c9440cd67baace5 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Wed, 14 Aug 2019 19:04:43 -0700
Subject: [PATCH] Disable @babel/plugin-transform-block-scoping
 "throwIfClosureRequired" option for tests

---
 scripts/jest/preprocessor.js | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/scripts/jest/preprocessor.js b/scripts/jest/preprocessor.js
index 44642ec91888d..b04daaee886b5 100644
--- a/scripts/jest/preprocessor.js
+++ b/scripts/jest/preprocessor.js
@@ -40,6 +40,10 @@ const babelOptions = {
     require.resolve('@babel/plugin-transform-react-jsx-source'),
 
     require.resolve('../babel/transform-prevent-infinite-loops'),
+
+    // This optimization is important for extremely performance-sensitive (e.g. React source).
+    // It's okay to disable it for tests.
+    [require.resolve('@babel/plugin-transform-block-scoping'), {throwIfClosureRequired: false}],
   ],
   retainLines: true,
 };