Is it possible to keep a service but return a specific value for a single method in a test

[handyCAPS]

I'm very sorry if this is a simple thing, but I can't get it to work and there doesn't seem to be any documentation on this. I have a component with a service that works fine with keep(), but I want to override one of its methods and return a specific value. I've tried to use keep() and then a mock(), but this does not work.

beforeEach(() => {
    return MockBuilder(BoardComponent, SharedModule)
      .keep(WordService)
      // All other methods disappear after adding this
      .mock(WordService, {
        checkWordInList: () => true,
      });
  });