---
- hosts: localhost
  # The gather_facts keyword has default values for its
  # options so module_defaults doesn't have much affect.
  gather_facts: no
  tags:
    - default_fact_module
  tasks:
    - name: set defaults for the action plugin
      gather_facts:
      module_defaults:
        gather_facts:
          gather_subset: min

    - assert:
        that: "gather_subset == ['min']"

    - name: set defaults for the module
      gather_facts:
      module_defaults:
        setup:
          gather_subset: '!all'

    - assert:
        that: "gather_subset == ['!all']"

    # Defaults for the action plugin win because they are
    # loaded first and options need to be omitted for
    # defaults to be used.
    - name: set defaults for the action plugin and module
      gather_facts:
      module_defaults:
        setup:
          gather_subset: '!all'
        gather_facts:
          gather_subset: min

    - assert:
        that: "gather_subset == ['min']"

    # The gather_facts 'smart' facts module is 'ansible.legacy.setup' by default.
    # If 'setup' (the unqualified name) is explicitly requested, FQCN module_defaults
    # would not apply.
    - name: set defaults for the fqcn module
      gather_facts:
      module_defaults:
        ansible.legacy.setup:
          gather_subset: '!all'

    - assert:
        that: "gather_subset == ['!all']"

- hosts: localhost
  gather_facts: no
  tags:
    - custom_fact_module
  tasks:
    - name: set defaults for the module
      gather_facts:
      module_defaults:
        ansible.legacy.setup:
          gather_subset: '!all'

    - assert:
        that:
          - "gather_subset == ['!all']"

    # Defaults for the action plugin win.
    - name: set defaults for the action plugin and module
      gather_facts:
      module_defaults:
        gather_facts:
          gather_subset: min
        ansible.legacy.setup:
          gather_subset: '!all'

    - assert:
        that:
          - "gather_subset == ['min']"