ansible/test/integration/targets/delegate_to/delegate_facts_block.yml

- hosts: testhost
  gather_facts: false
  tasks:
    - name: set var to delegated host directly
      set_fact: qq1=333
      delegate_facts: true
      delegate_to: localhost

    - name: ensure qq1 exists in localhost but not in testhost
      assert:
        that:
            - qq1 is undefined
            - "'qq1' in hostvars['localhost']"

    - name: set var to delegated host via inheritance
      block:
        - set_fact: qq2=333
      delegate_facts: true
      delegate_to: localhost

    - name: ensure qq2 exists in localhost but not in testhost
      assert:
        that:
            - qq2 is undefined
            - "'qq2' in hostvars['localhost']"