Spy helper for mocking out services.

spyHelper.ts

import { Provider, Type } from '@angular/core';
export type Mock<T> = T & { [P in keyof T]: T[P] & jasmine.Spy };
export class SpyHelper {

    public static createMagicalMock<T>(type: Type<T>): Mock<T> {
        const target: any = {};

        function installProtoMethods(proto: any) {
            if (proto === null || proto === Object.prototype) {
                return;
            }

            for (let key of Object.getOwnPropertyNames(proto)) {
                const descriptor = Object.getOwnPropertyDescriptor(proto, key)!;

                if (typeof descriptor.value === 'function' && key !== 'constructor') {
                    target[key] = jasmine.createSpy(key);
                }
            }

            installProtoMethods(Object.getPrototypeOf(proto));
        }

        installProtoMethods(type.prototype);

        return target;
    }

    public static provideMagicalMock<T>(type: Type<T>): Provider {
        return {
            provide: type,
            useFactory: () => SpyHelper.createMagicalMock(type),
        };
    }
}