From a34e4b69630ce713c0c25a5af66734c96b25f0c7 Mon Sep 17 00:00:00 2001
From: cexbrayat <cedric@ninja-squad.com>
Date: Tue, 3 Aug 2021 09:09:46 +0200
Subject: [PATCH] fix: spyOn should not rely on hasOwnProperty from the spied
 object

The `spyOn` function uses `hasOwnProperty` from the spied object, but this method can be unavailable,
for example if the object has the `null` prototype, or if it is a proxy that filters some keys.

This arises in Vue 3 projects where the proxies returned by the framework do not expose all methods,
and forces the testing library to manually patch the proxies with `hasOwnProperty` to let Jest do its work
https://github.com/vuejs/vue-test-utils-next/blob/23d3d3e1f4178a87de5023f5255e0623653affdc/src/mount.ts#L493-L495

This commit changes the code to use `Object.prototype.hasOwnProperty` and fixes this issue.
---
 CHANGELOG.md                                   |  4 ++++
 packages/jest-mock/src/__tests__/index.test.ts | 12 ++++++++++++
 packages/jest-mock/src/index.ts                |  5 ++++-
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index a6b1d88a6a8d..ad4935540360 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -14,6 +14,10 @@
 
 - `[docs]` Correct expects.assertions documentation by adding async/await for asynchronous function.
 
+### Fixes
+
+- `[jest-mock]` Fix `spyOn` to use `Object.prototype.hasOwnProperty` [#11721](https://github.com/facebook/jest/pull/11721)
+
 ## 27.0.6
 
 ### Fixes
diff --git a/packages/jest-mock/src/__tests__/index.test.ts b/packages/jest-mock/src/__tests__/index.test.ts
index 0266d24f2b7b..5c1159214359 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 not rely on hasOwnProperty', () => {
+      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 1b0330421124..885bf2ecf2d4 100644
--- a/packages/jest-mock/src/index.ts
+++ b/packages/jest-mock/src/index.ts
@@ -976,7 +976,10 @@ 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);