diff --git a/packages/jest-mock/src/__tests__/__fixtures__/class-mocks-types.ts b/packages/jest-mock/src/__tests__/__fixtures__/class-mocks-types.ts
index ccb2eae1fc4f..a6f8aa5634d8 100644
--- a/packages/jest-mock/src/__tests__/__fixtures__/class-mocks-types.ts
+++ b/packages/jest-mock/src/__tests__/__fixtures__/class-mocks-types.ts
@@ -52,3 +52,16 @@ export default class SuperTestClass {
 }
 
 export class TestClass extends SuperTestClass {}
+
+export function testFunction1() {
+  return 'testFunction1';
+}
+
+function testFunction() {
+  return 'testFunction2';
+}
+export const testFunction2 = testFunction;
+
+export const testFunction3 = () => {
+  return 'testFunction3';
+};
diff --git a/packages/jest-mock/src/__tests__/class-mocks-dual-import.test.ts b/packages/jest-mock/src/__tests__/class-mocks-dual-import.test.ts
index 610469e9deba..3bcc759e6d68 100644
--- a/packages/jest-mock/src/__tests__/class-mocks-dual-import.test.ts
+++ b/packages/jest-mock/src/__tests__/class-mocks-dual-import.test.ts
@@ -35,96 +35,4 @@ describe('Testing the mocking of a class hierarchy defined in multiple imports',
     expect(testClassInstance.testMethod()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
   });
-
-  it('can read a value from an instance getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass.prototype, 'testAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockTestAccessor';
-      });
-    const testClassInstance = new SuperTestClass();
-    expect(testClassInstance.testAccessor).toBe('mockTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can read a value from a superclass instance getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'testAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockTestAccessor';
-      });
-    const testClassInstance = new TestClass();
-    expect(testClassInstance.testAccessor).toBe('mockTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
-  it('can write a value to an instance setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass.prototype, 'testAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    const testClassInstance = new SuperTestClass();
-    testClassInstance.testAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can write a value to a superclass instance setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'testAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    const testClassInstance = new TestClass();
-    testClassInstance.testAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
-  it('can read a value from a static getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass, 'staticTestAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockStaticTestAccessor';
-      });
-    expect(SuperTestClass.staticTestAccessor).toBe('mockStaticTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can read a value from a superclass static getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass, 'staticTestAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockStaticTestAccessor';
-      });
-    expect(TestClass.staticTestAccessor).toBe('mockStaticTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
-  it('can write a value to a static setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass, 'staticTestAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    SuperTestClass.staticTestAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can write a value to a superclass static setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass, 'staticTestAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    TestClass.staticTestAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
 });
diff --git a/packages/jest-mock/src/__tests__/class-mocks-single-import.test.ts b/packages/jest-mock/src/__tests__/class-mocks-single-import.test.ts
index 9b354db44d95..078c0531ddf2 100644
--- a/packages/jest-mock/src/__tests__/class-mocks-single-import.test.ts
+++ b/packages/jest-mock/src/__tests__/class-mocks-single-import.test.ts
@@ -6,9 +6,32 @@
  *
  */
 
-import SuperTestClass, {TestClass} from './__fixtures__/class-mocks-types';
+import SuperTestClass, * as testTypes from './__fixtures__/class-mocks-types';
 jest.mock('./__fixtures__/class-mocks-types');
 
+describe('Testing the mocking of exported functions', () => {
+  it('can mock a directly exported function', () => {
+    jest.spyOn(testTypes, 'testFunction1').mockImplementation(() => {
+      return 'mockTestFunction';
+    });
+    expect(testTypes.testFunction1()).toBe('mockTestFunction');
+  });
+
+  it('can mock an indirectly exported function', () => {
+    jest.spyOn(testTypes, 'testFunction2').mockImplementation(() => {
+      return 'mockTestFunction';
+    });
+    expect(testTypes.testFunction2()).toBe('mockTestFunction');
+  });
+
+  it('can mock an indirectly exported anonymous function', () => {
+    jest.spyOn(testTypes, 'testFunction3').mockImplementation(() => {
+      return 'mockTestFunction';
+    });
+    expect(testTypes.testFunction3()).toBe('mockTestFunction');
+  });
+});
+
 describe('Testing the mocking of a class hierarchy defined in a single import', () => {
   it('can call an instance method - Auto-mocked class', () => {
     const mockTestMethod = jest
@@ -25,11 +48,11 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass instance method - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'testMethod')
+      .spyOn(testTypes.TestClass.prototype, 'testMethod')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    const testClassInstance = new TestClass();
+    const testClassInstance = new testTypes.TestClass();
     expect(testClassInstance.testMethod()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
   });
@@ -49,11 +72,11 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass instance method named "get" - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'get')
+      .spyOn(testTypes.TestClass.prototype, 'get')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    const testClassInstance = new TestClass();
+    const testClassInstance = new testTypes.TestClass();
     expect(testClassInstance.get()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
 
@@ -75,65 +98,17 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass instance method named "set" - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'set')
+      .spyOn(testTypes.TestClass.prototype, 'set')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    const testClassInstance = new TestClass();
+    const testClassInstance = new testTypes.TestClass();
     expect(testClassInstance.set()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
 
     mockTestMethod.mockClear();
   });
 
-  it('can read a value from an instance getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass.prototype, 'testAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockTestAccessor';
-      });
-    const testClassInstance = new SuperTestClass();
-    expect(testClassInstance.testAccessor).toBe('mockTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can read a value from a superclass instance getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'testAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockTestAccessor';
-      });
-    const testClassInstance = new TestClass();
-    expect(testClassInstance.testAccessor).toBe('mockTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
-  it('can write a value to an instance setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass.prototype, 'testAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    const testClassInstance = new SuperTestClass();
-    testClassInstance.testAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can write a value to a superclass instance setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass.prototype, 'testAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    const testClassInstance = new TestClass();
-    testClassInstance.testAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
   it('can call a static method - Auto-mocked class', () => {
     const mockTestMethod = jest
       .spyOn(SuperTestClass, 'staticTestMethod')
@@ -148,11 +123,11 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass static method - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass, 'staticTestMethod')
+      .spyOn(testTypes.TestClass, 'staticTestMethod')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    expect(TestClass.staticTestMethod()).toBe('mockTestMethod');
+    expect(testTypes.TestClass.staticTestMethod()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
   });
 
@@ -170,11 +145,11 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass static method named "get" - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass, 'get')
+      .spyOn(testTypes.TestClass, 'get')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    expect(TestClass.get()).toBe('mockTestMethod');
+    expect(testTypes.TestClass.get()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
 
     mockTestMethod.mockClear();
@@ -194,57 +169,13 @@ describe('Testing the mocking of a class hierarchy defined in a single import',
 
   it('can call a superclass static method named "set" - Auto-mocked class', () => {
     const mockTestMethod = jest
-      .spyOn(TestClass, 'set')
+      .spyOn(testTypes.TestClass, 'set')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
-    expect(TestClass.set()).toBe('mockTestMethod');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can read a value from a static getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass, 'staticTestAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockStaticTestAccessor';
-      });
-    expect(SuperTestClass.staticTestAccessor).toBe('mockStaticTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-
-    mockTestMethod.mockClear();
-  });
-
-  it('can read a value from a superclass static getter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass, 'staticTestAccessor', 'get')
-      .mockImplementation(() => {
-        return 'mockStaticTestAccessor';
-      });
-    expect(TestClass.staticTestAccessor).toBe('mockStaticTestAccessor');
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
-
-  it('can write a value to a static setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(SuperTestClass, 'staticTestAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    SuperTestClass.staticTestAccessor = '';
+    expect(testTypes.TestClass.set()).toBe('mockTestMethod');
     expect(mockTestMethod).toHaveBeenCalledTimes(1);
 
     mockTestMethod.mockClear();
   });
-
-  it('can write a value to a superclass static setter - Auto-mocked class', () => {
-    const mockTestMethod = jest
-      .spyOn(TestClass, 'staticTestAccessor', 'set')
-      .mockImplementation((_x: string) => {
-        return () => {};
-      });
-    TestClass.staticTestAccessor = '';
-    expect(mockTestMethod).toHaveBeenCalledTimes(1);
-  });
 });
diff --git a/packages/jest-mock/src/__tests__/class-mocks.test.ts b/packages/jest-mock/src/__tests__/class-mocks.test.ts
index 4b33c6c532dd..ea6b92f66465 100644
--- a/packages/jest-mock/src/__tests__/class-mocks.test.ts
+++ b/packages/jest-mock/src/__tests__/class-mocks.test.ts
@@ -14,11 +14,14 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass.prototype, 'testMethod').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'testMethod')
+      .mockImplementation(() => 'mockTestMethod');
     const testClassInstance = new TestClass();
     expect(testClassInstance.testMethod()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.testMethod()).toBe('testMethod');
   });
 
   it('can call a superclass instance method', () => {
@@ -30,11 +33,18 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass.prototype, 'testMethod').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'testMethod')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     const testClassInstance = new TestClass();
     expect(testClassInstance.testMethod()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.testMethod()).toBe('testMethod');
+    // eslint-disable-next-line no-prototype-builtins
+    expect(TestClass.prototype.hasOwnProperty('testMethod')).toBe(false);
   });
 
   it('can call an instance method named "get"', () => {
@@ -44,11 +54,16 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass.prototype, 'get').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'get')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     const testClassInstance = new TestClass();
     expect(testClassInstance.get()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.get()).toBe('get');
   });
 
   it('can call a superclass instance method named "get"', () => {
@@ -60,11 +75,18 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass.prototype, 'get').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'get')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     const testClassInstance = new TestClass();
     expect(testClassInstance.get()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.get()).toBe('get');
+    // eslint-disable-next-line no-prototype-builtins
+    expect(TestClass.prototype.hasOwnProperty('get')).toBe(false);
   });
 
   it('can call an instance method named "set"', () => {
@@ -74,11 +96,16 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass.prototype, 'set').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'set')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     const testClassInstance = new TestClass();
     expect(testClassInstance.set()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.set()).toBe('set');
   });
 
   it('can call a superclass instance method named "set"', () => {
@@ -90,11 +117,18 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass.prototype, 'set').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass.prototype, 'set')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     const testClassInstance = new TestClass();
     expect(testClassInstance.set()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.set()).toBe('set');
+    // eslint-disable-next-line no-prototype-builtins
+    expect(TestClass.prototype.hasOwnProperty('set')).toBe(false);
   });
 
   it('can read a value from an instance getter', () => {
@@ -104,13 +138,16 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest
+    const mockFn = jest
       .spyOn(TestClass.prototype, 'testMethod', 'get')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
     const testClassInstance = new TestClass();
     expect(testClassInstance.testMethod).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.testMethod).toBe('testMethod');
   });
 
   it('can read a value from an superclass instance getter', () => {
@@ -122,13 +159,16 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest
+    const mockFn = jest
       .spyOn(TestClass.prototype, 'testMethod', 'get')
       .mockImplementation(() => {
         return 'mockTestMethod';
       });
     const testClassInstance = new TestClass();
     expect(testClassInstance.testMethod).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(testClassInstance.testMethod).toBe('testMethod');
   });
 
   it('can write a value to an instance setter', () => {
@@ -147,6 +187,10 @@ describe('Testing the mocking of a class', () => {
     const testClassInstance = new TestClass();
     testClassInstance.testMethod = '';
     expect(mocktestMethod).toHaveBeenCalledTimes(1);
+
+    mocktestMethod.mockRestore();
+    testClassInstance.testMethod = '';
+    expect(mocktestMethod).toHaveBeenCalledTimes(0);
   });
 
   it('can write a value to a superclass instance setter', () => {
@@ -167,6 +211,10 @@ describe('Testing the mocking of a class', () => {
     const testClassInstance = new TestClass();
     testClassInstance.testMethod = '';
     expect(mocktestMethod).toHaveBeenCalledTimes(1);
+
+    mocktestMethod.mockRestore();
+    testClassInstance.testMethod = '';
+    expect(mocktestMethod).toHaveBeenCalledTimes(0);
   });
 
   it('can call a static method', () => {
@@ -176,10 +224,15 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass, 'testMethod').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass, 'testMethod')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     expect(TestClass.testMethod()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.testMethod()).toBe('testMethod');
   });
 
   it('can call a superclass static method', () => {
@@ -191,10 +244,15 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass, 'testMethod').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass, 'testMethod')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     expect(TestClass.testMethod()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.testMethod()).toBe('testMethod');
   });
 
   it('can call a static method named "get"', () => {
@@ -204,10 +262,13 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass, 'get').mockImplementation(() => {
+    const mockFn = jest.spyOn(TestClass, 'get').mockImplementation(() => {
       return 'mockTestMethod';
     });
     expect(TestClass.get()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.get()).toBe('get');
   });
 
   it('can call a superclass static method named "get"', () => {
@@ -219,10 +280,15 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass, 'get').mockImplementation(() => {
+    const mockFn = jest.spyOn(TestClass, 'get').mockImplementation(() => {
       return 'mockTestMethod';
     });
     expect(TestClass.get()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.get()).toBe('get');
+    // eslint-disable-next-line no-prototype-builtins
+    expect(TestClass.hasOwnProperty('get')).toBe(false);
   });
 
   it('can call a static method named "set"', () => {
@@ -232,10 +298,13 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass, 'set').mockImplementation(() => {
+    const mockFn = jest.spyOn(TestClass, 'set').mockImplementation(() => {
       return 'mockTestMethod';
     });
     expect(TestClass.set()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.set()).toBe('set');
   });
 
   it('can call a superclass static method named "set"', () => {
@@ -247,10 +316,15 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass, 'set').mockImplementation(() => {
+    const mockFn = jest.spyOn(TestClass, 'set').mockImplementation(() => {
       return 'mockTestMethod';
     });
     expect(TestClass.set()).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.set()).toBe('set');
+    // eslint-disable-next-line no-prototype-builtins
+    expect(TestClass.hasOwnProperty('set')).toBe(false);
   });
 
   it('can read a value from a static getter', () => {
@@ -260,10 +334,15 @@ describe('Testing the mocking of a class', () => {
       }
     }
 
-    jest.spyOn(TestClass, 'testMethod', 'get').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass, 'testMethod', 'get')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     expect(TestClass.testMethod).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.testMethod).toBe('testMethod');
   });
 
   it('can read a value from a superclass static getter', () => {
@@ -275,10 +354,15 @@ describe('Testing the mocking of a class', () => {
 
     class TestClass extends SuperTestClass {}
 
-    jest.spyOn(TestClass, 'testMethod', 'get').mockImplementation(() => {
-      return 'mockTestMethod';
-    });
+    const mockFn = jest
+      .spyOn(TestClass, 'testMethod', 'get')
+      .mockImplementation(() => {
+        return 'mockTestMethod';
+      });
     expect(TestClass.testMethod).toBe('mockTestMethod');
+
+    mockFn.mockRestore();
+    expect(TestClass.testMethod).toBe('testMethod');
   });
 
   it('can write a value to a static setter', () => {
@@ -296,6 +380,9 @@ describe('Testing the mocking of a class', () => {
       });
     TestClass.testMethod = '';
     expect(mocktestMethod).toHaveBeenCalledTimes(1);
+
+    mocktestMethod.mockRestore();
+    expect(mocktestMethod).toHaveBeenCalledTimes(0);
   });
 
   it('can write a value to a superclass static setter', () => {
diff --git a/packages/jest-mock/src/__tests__/index.test.ts b/packages/jest-mock/src/__tests__/index.test.ts
index 8f1436f4b042..71680852eca7 100644
--- a/packages/jest-mock/src/__tests__/index.test.ts
+++ b/packages/jest-mock/src/__tests__/index.test.ts
@@ -1264,7 +1264,9 @@ describe('moduleMocker', () => {
       }).toThrow('spyOn could not find an object to spy upon for method');
       expect(() => {
         moduleMocker.spyOn({}, 'method');
-      }).toThrow('method property does not exist');
+      }).toThrow(
+        'Cannot spy the method property because it is not a function; undefined given instead',
+      );
       expect(() => {
         moduleMocker.spyOn({method: 10}, 'method');
       }).toThrow(
@@ -1432,7 +1434,9 @@ describe('moduleMocker', () => {
       }).toThrow('spyOn could not find an object to spy upon for method');
       expect(() => {
         moduleMocker.spyOn({}, 'method');
-      }).toThrow('method property does not exist');
+      }).toThrow(
+        'Cannot spy the method property because it is not a function; undefined given instead',
+      );
       expect(() => {
         moduleMocker.spyOn({method: 10}, 'method');
       }).toThrow(
diff --git a/packages/jest-mock/src/__tests__/window-spy.test.ts b/packages/jest-mock/src/__tests__/window-spy.test.ts
new file mode 100644
index 000000000000..43285c041706
--- /dev/null
+++ b/packages/jest-mock/src/__tests__/window-spy.test.ts
@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @jest-environment jsdom
+ */
+
+/// <reference lib="dom" />
+
+/* eslint-env browser*/
+
+function exampleDispatch() {
+  window.dispatchEvent(new CustomEvent('event', {}));
+}
+
+describe('spy on `dispatchEvent`', () => {
+  const dispatchEventSpy = jest.spyOn(window, 'dispatchEvent');
+
+  it('should be called', () => {
+    exampleDispatch();
+
+    expect(dispatchEventSpy).toHaveBeenCalled();
+  });
+});
diff --git a/packages/jest-mock/src/index.ts b/packages/jest-mock/src/index.ts
index d0c6ba44ac8c..3c0b6f108bd5 100644
--- a/packages/jest-mock/src/index.ts
+++ b/packages/jest-mock/src/index.ts
@@ -535,10 +535,7 @@ export class ModuleMocker {
 
         if (!isReadonlyProp(object, prop)) {
           const propDesc = Object.getOwnPropertyDescriptor(object, prop);
-          if (
-            propDesc !== undefined &&
-            !(propDesc.get && prop == '__proto__')
-          ) {
+          if ((propDesc !== undefined && !propDesc.get) || object.__esModule) {
             slots.add(prop);
           }
         }
@@ -928,9 +925,7 @@ export class ModuleMocker {
     }
 
     this._getSlots(metadata.members).forEach(slot => {
-      let slotMock: Mocked<T>;
       const slotMetadata = (metadata.members && metadata.members[slot]) || {};
-
       if (slotMetadata.ref != null) {
         callbacks.push(
           (function (ref) {
@@ -938,40 +933,7 @@ export class ModuleMocker {
           })(slotMetadata.ref),
         );
       } else {
-        slotMock = this._generateMock(slotMetadata, callbacks, refs);
-
-        // For superclass accessor properties the subclass metadata contains the definitions
-        // for the getter and setter methods, and the superclass refs to them.
-        // The mock implementations are not available until the callbacks have been executed.
-        // Missing getter and setter refs will be resolved as their callbacks have been
-        // stacked before the setting of the accessor definition is stacked.
-
-        // In some cases, e.g. third-party APIs, a 'prototype' ancestor to be
-        // mocked has a function property called 'get'.  In this circumstance
-        // the 'prototype' property cannot be redefined and doing so causes an
-        // exception. Checks have been added for the 'configurable' and
-        // 'enumberable' properties present on true accessor property
-        // descriptors to prevent the attempt to replace the API.
-        if (
-          (slotMetadata.members?.get?.ref !== undefined ||
-            slotMetadata.members?.set?.ref !== undefined) &&
-          slotMetadata.members?.configurable &&
-          slotMetadata.members?.enumerable
-        ) {
-          callbacks.push(
-            (function (ref) {
-              return () => Object.defineProperty(mock, slot, ref);
-            })(slotMock as PropertyDescriptor),
-          );
-        } else if (
-          (slotMetadata.members?.get || slotMetadata.members?.set) &&
-          slotMetadata.members?.configurable &&
-          slotMetadata.members?.enumerable
-        ) {
-          Object.defineProperty(mock, slot, slotMock as PropertyDescriptor);
-        } else {
-          mock[slot] = slotMock;
-        }
+        mock[slot] = this._generateMock(slotMetadata, callbacks, refs);
       }
     });
 
@@ -1055,33 +1017,8 @@ export class ModuleMocker {
         ) {
           return;
         }
-
-        let descriptor = Object.getOwnPropertyDescriptor(component, slot);
-        let proto = Object.getPrototypeOf(component);
-        while (!descriptor && proto !== null) {
-          descriptor = Object.getOwnPropertyDescriptor(proto, slot);
-          proto = Object.getPrototypeOf(proto);
-        }
-
-        let slotMetadata: MockMetadata<T> | null = null;
-        if (descriptor?.get || descriptor?.set) {
-          // Specific case required for mocking class definitions imported via modules.
-          // In this case the class definitions are stored in accessor properties.
-          // All getters were previously ignored except where the containing object had __esModule == true
-          // Now getters are mocked the class definitions must still be read.
-          // @ts-expect-error ignore type mismatch
-          if (component.__esModule) {
-            // @ts-expect-error no index signature
-            slotMetadata = this.getMetadata<T>(component[slot], refs);
-          } else {
-            // @ts-expect-error ignore type mismatch
-            slotMetadata = this.getMetadata<T>(descriptor, refs);
-          }
-        } else {
-          // @ts-expect-error no index signature
-          slotMetadata = this.getMetadata<T>(component[slot], refs);
-        }
-
+        // @ts-expect-error no index signature
+        const slotMetadata = this.getMetadata<T>(component[slot], refs);
         if (slotMetadata) {
           if (!members) {
             members = {};
@@ -1151,6 +1088,12 @@ export class ModuleMocker {
     methodKey: K,
     accessType?: 'get' | 'set',
   ) {
+    if (typeof object !== 'object' && typeof object !== 'function') {
+      throw new Error(
+        `Cannot spyOn on a primitive value; ${this._typeOf(object)} given`,
+      );
+    }
+
     if (!object) {
       throw new Error(
         `spyOn could not find an object to spy upon for ${String(methodKey)}`,
@@ -1161,120 +1104,124 @@ export class ModuleMocker {
       throw new Error('No property name supplied');
     }
 
-    if (accessType && accessType != 'get' && accessType != 'set') {
-      throw new Error('Invalid accessType supplied');
+    if (accessType) {
+      return this._spyOnProperty(object, methodKey, accessType);
     }
 
-    if (typeof object !== 'object' && typeof object !== 'function') {
-      throw new Error(
-        `Cannot spyOn on a primitive value; ${this._typeOf(object)} given`,
+    const original = object[methodKey];
+
+    if (!this.isMockFunction(original)) {
+      if (typeof original !== 'function') {
+        throw new Error(
+          `Cannot spy the ${String(
+            methodKey,
+          )} property because it is not a function; ${this._typeOf(
+            original,
+          )} given instead`,
+        );
+      }
+
+      const isMethodOwner = Object.prototype.hasOwnProperty.call(
+        object,
+        methodKey,
       );
+
+      let descriptor = Object.getOwnPropertyDescriptor(object, methodKey);
+      let proto = Object.getPrototypeOf(object);
+
+      while (!descriptor && proto !== null) {
+        descriptor = Object.getOwnPropertyDescriptor(proto, methodKey);
+        proto = Object.getPrototypeOf(proto);
+      }
+
+      let mock: Mock;
+
+      if (descriptor && descriptor.get) {
+        const originalGet = descriptor.get;
+        mock = this._makeComponent({type: 'function'}, () => {
+          descriptor!.get = originalGet;
+          Object.defineProperty(object, methodKey, descriptor!);
+        });
+        descriptor.get = () => mock;
+        Object.defineProperty(object, methodKey, descriptor);
+      } else {
+        mock = this._makeComponent({type: 'function'}, () => {
+          if (isMethodOwner) {
+            object[methodKey] = original;
+          } else {
+            delete object[methodKey];
+          }
+        });
+        // @ts-expect-error overriding original method with a Mock
+        object[methodKey] = mock;
+      }
+
+      mock.mockImplementation(function (this: unknown) {
+        return original.apply(this, arguments);
+      });
     }
 
-    let descriptor = Object.getOwnPropertyDescriptor(object, methodKey);
-    let proto = Object.getPrototypeOf(object);
+    return object[methodKey];
+  }
+
+  private _spyOnProperty<T extends object, K extends PropertyLikeKeys<T>>(
+    obj: T,
+    propertyKey: K,
+    accessType: 'get' | 'set',
+  ): Mock<() => T> {
+    let descriptor = Object.getOwnPropertyDescriptor(obj, propertyKey);
+    let proto = Object.getPrototypeOf(obj);
+
     while (!descriptor && proto !== null) {
-      descriptor = Object.getOwnPropertyDescriptor(proto, methodKey);
+      descriptor = Object.getOwnPropertyDescriptor(proto, propertyKey);
       proto = Object.getPrototypeOf(proto);
     }
+
     if (!descriptor) {
-      throw new Error(`${String(methodKey)} property does not exist`);
-    }
-    if (!descriptor.configurable) {
-      throw new Error(`${String(methodKey)} is not declared configurable`);
+      throw new Error(`${String(propertyKey)} property does not exist`);
     }
 
-    if (this.isMockFunction(descriptor.value)) {
-      return object[methodKey];
-    } else if (accessType == 'get' && this.isMockFunction(descriptor.get)) {
-      return descriptor.get;
-    } else if (accessType == 'set' && this.isMockFunction(descriptor.set)) {
-      return descriptor.set;
+    if (!descriptor.configurable) {
+      throw new Error(`${String(propertyKey)} is not declared configurable`);
     }
 
-    if (accessType) {
-      if (typeof descriptor[accessType] !== 'function') {
-        throw new Error(
-          `Cannot spy the ${String(accessType)} ${String(
-            methodKey,
-          )} property because it is not a function;
-          ${this._typeOf(descriptor?.[accessType])} given instead`,
-        );
-      }
-    } else if (typeof descriptor.value !== 'function') {
+    if (!descriptor[accessType]) {
       throw new Error(
-        `Cannot spy the ${String(
-          methodKey,
-        )} property because it is not a function; ${this._typeOf(
-          descriptor.value,
-        )} given instead`,
+        `Property ${String(
+          propertyKey,
+        )} does not have access type ${accessType}`,
       );
     }
 
-    let mock: Mock;
+    const original = descriptor[accessType];
 
-    if (accessType == 'get' && descriptor.get) {
-      const originalAccessor = descriptor.get;
-      mock = this._makeComponent(
-        {
-          type: 'function',
-        },
-        () => {
-          descriptor![accessType] = originalAccessor;
-          Object.defineProperty(object, methodKey, descriptor!);
-        },
-      );
-
-      descriptor[accessType] = mock;
-      mock.mockImplementation(function (this: unknown) {
-        return originalAccessor.call(this);
-      });
-      Object.defineProperty(object, methodKey, descriptor);
-    } else if (accessType == 'set' && descriptor.set) {
-      const originalAccessor = descriptor.set;
-      mock = this._makeComponent(
-        {
-          type: 'function',
-        },
-        () => {
-          descriptor![accessType] = originalAccessor;
-          Object.defineProperty(object, methodKey, descriptor!);
-        },
-      );
+    if (!this.isMockFunction(original)) {
+      if (typeof original !== 'function') {
+        throw new Error(
+          `Cannot spy the ${String(
+            propertyKey,
+          )} property because it is not a function; ${this._typeOf(
+            original,
+          )} given instead`,
+        );
+      }
 
-      descriptor[accessType] = mock;
-      mock.mockImplementation(function (this: unknown) {
-        return originalAccessor.call(this, arguments[0]);
+      descriptor[accessType] = this._makeComponent({type: 'function'}, () => {
+        // @ts-expect-error: mock is assignable
+        descriptor![accessType] = original;
+        Object.defineProperty(obj, propertyKey, descriptor!);
       });
-      Object.defineProperty(object, methodKey, descriptor);
-    } else {
-      const isMethodOwner = Object.prototype.hasOwnProperty.call(
-        object,
-        methodKey,
-      );
-      const original = descriptor;
 
-      mock = this._makeComponent(
-        {
-          type: 'function',
-        },
-        () => {
-          if (isMethodOwner) {
-            object[methodKey] = original.value;
-          } else {
-            delete object[methodKey];
-          }
-        },
-      );
-
-      // @ts-expect-error overriding original method with a Mock
-      object[methodKey] = mock;
-      mock.mockImplementation(function (this: unknown) {
-        return original.value.apply(this, arguments);
+      (descriptor[accessType] as Mock<() => T>).mockImplementation(function (
+        this: unknown,
+      ) {
+        // @ts-expect-error - wrong context
+        return original.apply(this, arguments);
       });
     }
 
-    return mock;
+    Object.defineProperty(obj, propertyKey, descriptor);
+    return descriptor[accessType] as Mock<() => T>;
   }
 
   clearAllMocks(): void {
@@ -1291,7 +1238,7 @@ export class ModuleMocker {
     this._spyState = new Set();
   }
 
-  private _typeOf(value: any): string {
+  private _typeOf(value: unknown): string {
     return value == null ? `${value}` : typeof value;
   }