From ec3c183668da357104d23dc91008cf23bcae2292 Mon Sep 17 00:00:00 2001
From: Henry Zhu <hi@henryzoo.com>
Date: Sun, 28 Feb 2016 21:27:27 -0500
Subject: [PATCH] Fix: Add parens for unary arrow function

Fixes T7157
---
 packages/babel-generator/src/node/parentheses.js              | 4 ++++
 .../test/fixtures/parentheses/unary-arrow-function/actual.js  | 3 +++
 .../fixtures/parentheses/unary-arrow-function/expected.js     | 3 +++
 3 files changed, 10 insertions(+)
 create mode 100644 packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/actual.js
 create mode 100644 packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/expected.js

diff --git a/packages/babel-generator/src/node/parentheses.js b/packages/babel-generator/src/node/parentheses.js
index d5d098c66f..0c2bba3c5a 100644
--- a/packages/babel-generator/src/node/parentheses.js
+++ b/packages/babel-generator/src/node/parentheses.js
@@ -204,6 +204,10 @@ export function ArrowFunctionExpression(node: Object, parent: Object): boolean {
     return true;
   }
 
+  if (t.isUnaryExpression(parent)) {
+    return true;
+  }
+
   return UnaryLike(node, parent);
 }
 
diff --git a/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/actual.js b/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/actual.js
new file mode 100644
index 0000000000..a527c3b975
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/actual.js
@@ -0,0 +1,3 @@
+void (() => {});
+typeof (() => {});
+!(() => {});
diff --git a/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/expected.js b/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/expected.js
new file mode 100644
index 0000000000..a527c3b975
--- /dev/null
+++ b/packages/babel-generator/test/fixtures/parentheses/unary-arrow-function/expected.js
@@ -0,0 +1,3 @@
+void (() => {});
+typeof (() => {});
+!(() => {});