handlersFromFile.yml

- name: handler B
  debug: msg="Handler B"

testHandlers.yml

- hosts: all
  user: vagrant

  tasks:
  - name: task to notify handler A (local)
    shell: touch nn
    notify: handler A

  - name: task to notify handler B (from file)
    shell: touch nn
    notify: handler B

  - name: task to notify non-existent handler 
    shell: touch nn
    notify: handler non-exist # I would like an error here


  handlers:
  - name: handler A
    debug: msg="Handler A"

  - include: handlersFromFile.yml

  - include: nonexist.yml  # I would like an error here

tasks:

• include: handlers/handlersFromFile.yml
• name: task to notify handler A (local)
  shell: touch nn
  notify: handler A
• name: task to notify handler B (from file)
  shell: touch nn
  notify: handler B
• name: task to notify non-existent handler
  shell: touch nn
  notify: handler non-exist # I would like an error here