---

- name: Show how ansible defer variable evaluation to the last moment
  gather_facts: no
  hosts: localhost
  tasks:
  - name: Shows usage of interdependant variables
    block:
    - debug:
        msg: '{{ abcd }}'
    - name: Unit tests
      assert:
        that:
        - abcd == "aadd"
    vars:
      a: "a"
      b: '{{ a }}'
      ab: '{{ a }}{{ b }}'
      abcd: '{{ ab }}{{ cd }}'
      cd: '{{ c }}{{ d }}'
      c: '{{ d }}'
      d: "d"
  
  - name: Create a temporary directory
    tempfile: 
      state: directory
    register: tempfile

  - name: Shows that variables are evaluated when used and not when assigned
    block:
    - name: Nope, the file does not exists...
      set_fact:
        test_output1: '{{ test_variable }}'
      register: task1
      ignore_errors: true

    - name: Create the file
      file:
        path: '{{ test_file }}'
        state: touch

    - name: Now, it should be fine...
      set_fact:
        test_output2: '{{ test_variable }}'
      register: task2
      ignore_errors: true

    - name: Unit tests
      assert:
        that:
        - task1 is failed
        - task2 is not failed
        - test_output1 is not defined
        - test_output2 is defined
    vars:
      test_file: '{{ tempfile.path }}/i-am-here'
      test_variable: '{{ lookup(''file'', test_file) }}'