refactor(jest-mock): clean up internal typings more (#13575)

Author: mrazauskas

packages/jest-mock/src/index.ts

@@ -1089,12 +1089,11 @@ export class ModuleMocker {
     methodKey: K,
   ): V extends ClassLike | FunctionLike ? Spied<V> : never;
 
-  // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
-  spyOn<T extends object, K extends PropertyLikeKeys<T>>(
+  spyOn<T extends object>(
     object: T,
-    methodKey: K,
+    methodKey: keyof T,
     accessType?: 'get' | 'set',
-  ) {
+  ): MockInstance {
     if (typeof object !== 'object' && typeof object !== 'function') {
       throw new Error(
         `Cannot spyOn on a primitive value; ${this._typeOf(object)} given`,
@@ -1168,16 +1167,16 @@ export class ModuleMocker {
       });
     }
 
-    return object[methodKey];
+    return object[methodKey] as Mock;
   }
 
-  private _spyOnProperty<T extends object, K extends PropertyLikeKeys<T>>(
-    obj: T,
-    propertyKey: K,
+  private _spyOnProperty<T extends object>(
+    object: T,
+    propertyKey: keyof T,
     accessType: 'get' | 'set',
-  ): Mock<() => T> {
-    let descriptor = Object.getOwnPropertyDescriptor(obj, propertyKey);
-    let proto = Object.getPrototypeOf(obj);
+  ): MockInstance {
+    let descriptor = Object.getOwnPropertyDescriptor(object, propertyKey);
+    let proto = Object.getPrototypeOf(object);
 
     while (!descriptor && proto !== null) {
       descriptor = Object.getOwnPropertyDescriptor(proto, propertyKey);
@@ -1216,19 +1215,19 @@ export class ModuleMocker {
       descriptor[accessType] = this._makeComponent({type: 'function'}, () => {
         // @ts-expect-error: mock is assignable
         descriptor![accessType] = original;
-        Object.defineProperty(obj, propertyKey, descriptor!);
+        Object.defineProperty(object, propertyKey, descriptor!);
       });
 
-      (descriptor[accessType] as Mock<() => T>).mockImplementation(function (
+      (descriptor[accessType] as Mock).mockImplementation(function (
         this: unknown,
       ) {
         // @ts-expect-error - wrong context
         return original.apply(this, arguments);
       });
     }
 
-    Object.defineProperty(obj, propertyKey, descriptor);
-    return descriptor[accessType] as Mock<() => T>;
+    Object.defineProperty(object, propertyKey, descriptor);
+    return descriptor[accessType] as Mock;
   }
 
   clearAllMocks(): void {