From e00529db9b9ce84c968a80829dfd1afea4853e40 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miguel=20Jim=C3=A9nez=20Es=C3=BAn?=
 <mjesun@users.noreply.github.com>
Date: Wed, 29 Nov 2017 18:32:02 +0000
Subject: [PATCH] Make "weak" optional dependency and check it at runtime
 (#4984)

* Make "weak" optional dependency and check it at runtime

* Update index.js
---
 packages/jest-leak-detector/package.json |  4 +++-
 packages/jest-leak-detector/src/index.js | 12 +++++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/packages/jest-leak-detector/package.json b/packages/jest-leak-detector/package.json
index 4cd1e9bf41e5..79be99fda730 100644
--- a/packages/jest-leak-detector/package.json
+++ b/packages/jest-leak-detector/package.json
@@ -8,7 +8,9 @@
   "license": "MIT",
   "main": "build/index.js",
   "dependencies": {
-    "pretty-format": "^21.2.1",
+    "pretty-format": "^21.2.1"
+  },
+  "optionalDependencies": {
     "weak": "^1.0.1"
   }
 }
diff --git a/packages/jest-leak-detector/src/index.js b/packages/jest-leak-detector/src/index.js
index 7649aa26b770..33e6f5787350 100644
--- a/packages/jest-leak-detector/src/index.js
+++ b/packages/jest-leak-detector/src/index.js
@@ -12,7 +12,6 @@
 import prettyFormat from 'pretty-format';
 import v8 from 'v8';
 import vm from 'vm';
-import weak from 'weak';
 
 const PRIMITIVE_TYPES = new Set([
   'undefined',
@@ -35,6 +34,17 @@ export default class {
       );
     }
 
+    let weak;
+
+    try {
+      weak = require('weak');
+    } catch (err) {
+      throw new Error(
+        'The leaking detection mechanism requires the "weak" package to work. ' +
+          'Please make sure that you can install the native dependency on your platform.',
+      );
+    }
+
     weak(value, () => (this._isReferenceBeingHeld = false));
     this._isReferenceBeingHeld = true;