fix: spyOn should not rely on hasOwnProperty from the spied object (#…

…11721)
jestjs · Aug 16, 2021 · f3ae13c · f3ae13c
1 parent cccc155
commit f3ae13c
Show file tree

Hide file tree

Showing 3 changed files with 17 additions and 1 deletion.
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Fixes
 
 - `[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
@@ -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
@@ -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);