ansible/test/integration/targets/blockinfile/tasks/validate.yml

- name: EXPECTED FAILURE test improper validate
  blockinfile:
    path: "{{ remote_tmp_dir }}/validate.txt"
    block: |
      line1
      line2      
    create: yes
    validate: grep
  ignore_errors: yes

- name: EXPECTED FAILURE test failure to validate
  blockinfile:
    path: "{{ remote_tmp_dir }}/validate.txt"
    block: |
      line1
      line2      
    create: yes
    validate: grep line47 %s
  ignore_errors: yes

- name: Test proper validate
  blockinfile:
    path: "{{ remote_tmp_dir }}/validate.txt"
    block: |
      line1
      line2      
    create: yes
    validate: grep line1 %s