From f0a56e001193156135f8062833f5b92d6553e7fe Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?C=C3=A9dric=20Exbrayat?=
 <cexbrayat@users.noreply.github.com>
Date: Mon, 16 Aug 2021 10:32:15 +0200
Subject: [PATCH] fix: spyOn should not rely on hasOwnProperty from the spied
 object (#11721)

---
 CHANGELOG.md                                   |  1 +
 packages/jest-mock/src/__tests__/index.test.ts | 12 ++++++++++++
 packages/jest-mock/src/index.ts                |  5 ++++-
 3 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6eeedf0c6ff4..36487ee201c4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 - `[jest-types]` Compat with `@types/node` v16 ([#11645](https://github.com/facebook/jest/pull/11645))
 - `[jest-environment-node]` Add `Event` and `EventTarget` to node global environment. ([#11705](https://github.com/facebook/jest/issues/11705))
+- `[jest-mock]` Fix `spyOn` to use `Object.prototype.hasOwnProperty` [#11721](https://github.com/facebook/jest/pull/11721)
 
 ### Chore & Maintenance
 
diff --git a/packages/jest-mock/src/__tests__/index.test.ts b/packages/jest-mock/src/__tests__/index.test.ts
index 730b6a92e4ed..854d79a1c7b7 100644
--- a/packages/jest-mock/src/__tests__/index.test.ts
+++ b/packages/jest-mock/src/__tests__/index.test.ts
@@ -1216,6 +1216,18 @@ describe('moduleMocker', () => {
       expect(originalCallArguments[1]).toBe(secondArg);
       expect(spy).not.toHaveBeenCalled();
     });
+
+    it('should work with object of null prototype', () => {
+      const Foo = Object.assign(Object.create(null), {
+        foo() {},
+      });
+
+      const spy = moduleMocker.spyOn(Foo, 'foo');
+
+      Foo.foo();
+
+      expect(spy).toHaveBeenCalled();
+    });
   });
 
   describe('spyOnProperty', () => {
diff --git a/packages/jest-mock/src/index.ts b/packages/jest-mock/src/index.ts
index 93274dd4d47c..bdd7ac55d408 100644
--- a/packages/jest-mock/src/index.ts
+++ b/packages/jest-mock/src/index.ts
@@ -974,7 +974,10 @@ export class ModuleMocker {
         );
       }
 
-      const isMethodOwner = object.hasOwnProperty(methodName);
+      const isMethodOwner = Object.prototype.hasOwnProperty.call(
+        object,
+        methodName,
+      );
 
       let descriptor = Object.getOwnPropertyDescriptor(object, methodName);
       let proto = Object.getPrototypeOf(object);