fix(mock): consider modules as objects (#13513)

Author: Tofandel

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 ### Fixes
 
+- `[jest-mock]` Treat cjs modules as objects so they can be mocked ([#13513](https://github.com/facebook/jest/pull/13513))
+
 ### Chore & Maintenance
 
 - `[@jest/transform]` Update `convert-source-map` ([#13509](https://github.com/facebook/jest/pull/13509))

packages/jest-mock/src/__tests__/index.test.ts

@@ -213,6 +213,20 @@ describe('moduleMocker', () => {
       expect(mock.enumGetter).toBeDefined();
     });
 
+    it('handles custom toString of transpiled modules', () => {
+      const foo = Object.defineProperties(
+        {foo: 'bar'},
+        {
+          __esModule: {value: true},
+          [Symbol.toStringTag]: {value: 'Module'},
+        },
+      );
+      const mock = moduleMocker.generateFromMetadata(
+        moduleMocker.getMetadata(foo),
+      );
+      expect(mock.foo).toBeDefined();
+    });
+
     it('mocks ES2015 non-enumerable methods', () => {
       class ClassFoo {
         foo() {}

packages/jest-mock/src/index.ts

@@ -426,7 +426,7 @@ function getType(ref?: unknown): MockMetadataType | null {
     return 'function';
   } else if (Array.isArray(ref)) {
     return 'array';
-  } else if (typeName === 'Object') {
+  } else if (typeName === 'Object' || typeName === 'Module') {
     return 'object';
   } else if (
     typeName === 'Number' ||