[DNM] Confirming unit test for synchronize plugin

Signed-off-by: Hideki Saito <saito@fgrep.org>

changelogs/fragments/351_dnm_unit_test.yml

@@ -0,0 +1,3 @@
+---
+trivial:
+- confirming unit tet for synchronize.

tests/unit/plugins/action/test_synchronize.py

@@ -43,6 +43,10 @@ with open('task_vars.json', 'wb') as f:
 '''
 
 
+class Dummy(object):
+    pass
+
+
 class BreakPoint(Exception):
     pass
 
@@ -55,6 +59,7 @@ class TaskMock(object):
     become = None
     become_user = None
     become_method = None
+    check_mode = False
 
 
 class StdinMock(object):