title: NestJs Testing with CACHE_MANAGER injected
body: <p>I have some service in which I inject the CACHE_MANAGER in the constructor</p>
  <pre><code>import { CACHE_MANAGER, Inject, Injectable } from '@nestjs/common';
  import { Cache } from 'cache-manager';
  ...
  export class ManagerService {
     constructor(@Inject(CACHE_MANAGER) private cacheManager: Cache) {}
     ...
  }
  </code></pre>
  <p>That gives me an error when I test the modules the import those service</p>
  <p><code>Nest can't resolve dependencies of the ManagerService (?). Please make sure that the argument CACHE_MANAGER at index [0] is available in the Web3ManagerService context.</code></p>
  <p>I'm relatively new to NestJs so I really cannot figure out how to solve it</p>