fix(jest): fix for incorrect typing of SpyObject for Jest

Author: dirkluijk

projects/spectator/jest/src/mock.ts

@@ -1,7 +1,7 @@
 import { Provider, Type } from '@angular/core';
 import { CompatibleSpy, SpyObject as BaseSpyObject, installProtoMethods } from '@netbasal/spectator';
 
-export type SpyObject<T> = BaseSpyObject<T> & { [P in keyof T]: T[P] & jest.Mock<T> };
+export type SpyObject<T> = BaseSpyObject<T> & { [P in keyof T]: T[P] & (T[P] extends (...args: any[]) => infer R ? jest.Mock<R> : T[P]) };
 
 export function createSpyObject<T>(type: Type<T>, template?: Partial<Record<keyof T, any>>): SpyObject<T> {
   const mock: any = template || {};

projects/spectator/package.json

@@ -27,5 +27,8 @@
     "jquery": "3.3.1",
     "schematics-utilities": "^1.1.1"
   },
+  "peerDependencies": {
+    "typescript": ">= 2.8.0"
+  },
   "schematics": "./schematics/collection.json"
 }