diff --git a/changelogs/fragments/353_ci_fix_unittest_for_synchronize.yml b/changelogs/fragments/353_ci_fix_unittest_for_synchronize.yml
new file mode 100644
index 0000000..190b9f9
--- /dev/null
+++ b/changelogs/fragments/353_ci_fix_unittest_for_synchronize.yml
@@ -0,0 +1,3 @@
+---
+trivial:
+- CI tests - added check_mode attribute to TaskMock class for synchronize plugin unit test (https://github.com/ansible-collections/ansible.posix/issues/352).
diff --git a/tests/unit/plugins/action/test_synchronize.py b/tests/unit/plugins/action/test_synchronize.py
index bc1efca..40e489d 100644
--- a/tests/unit/plugins/action/test_synchronize.py
+++ b/tests/unit/plugins/action/test_synchronize.py
@@ -55,6 +55,7 @@ class TaskMock(object):
     become = None
     become_user = None
     become_method = None
+    check_mode = False
 
 
 class StdinMock(object):