---
- hosts: localhost
  connection: local
  gather_facts: no
  tasks:
  - add_host:
      name: host1
      ansible_connection: local
      ansible_host: 127.0.0.1

- hosts: all
  gather_facts: no
  tasks:
    - debug:
        msg: "{{ hostvars['host1']['x'] }}"
      register: x_1
    - debug:
        msg: "{{ hostvars['host1']['y'] }}"
      register: y_1
    - debug:
        msg: "{{ hostvars_['x'] }}"
      vars:
        hostvars_: "{{ hostvars['host1'] }}"
      register: x_2
    - debug:
        msg: "{{ hostvars_['y'] }}"
      vars:
        hostvars_: "{{ hostvars['host1'] }}"
      register: y_2

    - assert:
        that:
          - x_1 == x_2
          - y_1 == y_2
          - x_1 == y_1

    - debug:
        msg: "{{ hostvars['host1']['nested_x']['value'] }}"
      register: x_1
    - debug:
        msg: "{{ hostvars['host1']['nested_y']['value'] }}"
      register: y_1
    - debug:
        msg: "{{ hostvars_['nested_x']['value'] }}"
      vars:
        hostvars_: "{{ hostvars['host1'] }}"
      register: x_2
    - debug:
        msg: "{{ hostvars_['nested_y']['value'] }}"
      vars:
        hostvars_: "{{ hostvars['host1'] }}"
      register: y_2

    - assert:
        that:
          - x_1 == x_2
          - y_1 == y_2
          - x_1 == y_1