ansible - example of asserting that vars are defined with_items

output

PLAY [localhost] ************************************************************** 

GATHERING FACTS *************************************************************** 
$ ansible-playbook --version
ansible-playbook 1.9.3
  configured module search path = ~/git/ansible-modules-core:~/git/ansible-modules-extra:./library
  
$ ansible-playbook play.yml

ok: [localhost]

TASK: [assert ] *************************************************************** 
ok: [localhost] => (item=foo)
failed: [localhost] => (item=bar) => {"assertion": "bar is defined", "evaluated_to": false, "failed": true, "item": "bar"}
failed: [localhost] => (item=abc) => {"assertion": "abc is defined", "evaluated_to": false, "failed": true, "item": "abc"}
failed: [localhost] => (item=def) => {"assertion": "def is defined", "evaluated_to": false, "failed": true, "item": "def"}

FATAL: all hosts have already failed -- aborting

PLAY RECAP ******************************************************************** 
           to retry, use: --limit @/Users/glynch/assert_vars_defined.retry

localhost                  : ok=1    changed=0    unreachable=0    failed=1   

play.yml

---                                                                                                                          
- hosts: localhost
  vars:
    foo: bar
  tasks:
  - assert: { that: "{{ item }} is defined" }
    with_items: 
      - foo
      - bar
      - abc
      - def