I have written a test which should check if function working properly, but it is working with instance of database column (user).

I am not sure why function not even called.

here is the test, i thought it should call addPostToUser properly because i define postOwner as User instance but it is not working

describe('addPostToUser', () => {
      it('should add post to user', async () => {
        const postId = 'postid';
        const postOwner: User = {
          id: 'userid',
          name: 'User One',
          email: '[email protected]',
          posts: [],
        } as User;
      

        await userService.addPostToUser(postOwner.id, postId);
      
        expect(postOwner.posts).toContain(postId);
      });
    });

here is the function

async addPostToUser(userId: string, postId: string): Promise<void> {
    const user = await User.findOne({ where: { id: userId } });

    if (user) {
      await User.update(
        { posts: [...(user.posts || []), postId] },
        { where: { id: userId } },
      );
    }
  }

here is results

● UserModule › userService › addPostToUser › should add post to user

    expect(received).toContain(expected) // indexOf

    Expected value: "postid"
    Received array: []

      101 |         await userService.addPostToUser(postOwner.id, postId);
      102 |
    > 103 |         expect(postOwner.posts).toContain(postId);
          |                                 ^
      104 |       });
      105 |     });
      106 |   });