callback: record handler tasks too

It turns out that we had been missing out on handler tasks because we
need to use the hook "v2_playbook_on_handler_task_start" for those.

Fixes: https://github.com/ansible-community/ara/issues/178
Change-Id: Id05ba581fb22eee26270c7f4bccc3445e87b5d3b

ara/plugins/callback/ara_default.py

@@ -304,6 +304,11 @@ class CallbackModule(CallbackBase):
 
         return self.play
 
+    def v2_playbook_on_handler_task_start(self, task):
+        self.log.debug("v2_playbook_on_handler_task_start")
+        # TODO: Why doesn't `v2_playbook_on_handler_task_start` have is_conditional ?
+        self.v2_playbook_on_task_start(task, False, handler=True)
+
     def v2_playbook_on_task_start(self, task, is_conditional, handler=False):
         self.log.debug("v2_playbook_on_task_start")
         self._end_task()

tests/integration/roles/smoke-tests/handlers/main.yaml

@@ -0,0 +1,7 @@
+# Copyright (c) 2020 The ARA Records Ansible authors
+# GNU General Public License v3.0+ (see COPYING or https://www.gnu.org/licenses/gpl-3.0.txt)
+
+- name: handler
+  debug:
+    msg: hi, this is a handler task
+  register: _handler_run

tests/integration/roles/smoke-tests/tasks/test-ops.yaml

@@ -49,3 +49,16 @@
 - name: Test for XSS
   command: echo "<script>alert(document.cookie)</script>"
   changed_when: False
+
+- name: Notify something for a handler task
+  command: /bin/true
+  notify:
+    - handler
+
+- name: Flush handlers
+  meta: flush_handlers
+
+- name: Assert that handler task has run
+  assert:
+    that:
+      - _handler_run is success