file_filters.yml

---
# Test filter_plugins/file_filters

- name: file_filters
  hosts: localhost
  gather_facts: false

  vars:
    test_string: "test string"
    test_file1: "test_file1.txt"
    test_file2: "test_file2.txt"
    list1_files:
      - test_file1.txt
      - test_file2.txt
    list2_files:
      - test_file3.txt
      - test_file2.txt

  tasks:
    - name: "No.1 String is in file"
      debug:
        msg: "{{ test_string }} found in {{ test_file1 }}"
      when: test_file1|file_search(test_string)
      tags: t1

    - name: "No.1 String is in file"
      debug:
        msg: "{{ test_file1|file_search(test_string) }}"
      tags: t1a

    - name: "No.2 String is NOT in file"
      debug:
        msg: "{{ test_string }} found in {{ test_file2 }}"
      when: test_file2|file_search(test_string)
      tags: t2

    - name: "No.3 String is in list of files"
      debug:
        msg: "{{ test_string }} found"
      when: list1_files|file_list_search(test_string)
      tags: t3

    - name: "No.4 String is NOT in list of files"
      debug:
        msg: "{{ test_string }} found"
      when: list2_files|file_list_search(test_string)
      tags: t4

...