diff --git a/test/units/modules/monitoring/test_circonus_annotation.py b/test/units/modules/monitoring/test_circonus_annotation.py
new file mode 100644
index 00000000000..7db9d082b99
--- /dev/null
+++ b/test/units/modules/monitoring/test_circonus_annotation.py
@@ -0,0 +1,174 @@
+# -*- coding: utf-8 -*-
+
+import io
+import json
+import uuid
+from urllib3.response import HTTPResponse
+
+from ansible.compat.tests import unittest
+from ansible.compat.tests.mock import patch
+from ansible.module_utils import basic
+from ansible.module_utils._text import to_bytes
+from ansible.modules.monitoring import circonus_annotation
+
+
+def set_module_args(args):
+    args = json.dumps({'ANSIBLE_MODULE_ARGS': args})
+    basic._ANSIBLE_ARGS = to_bytes(args)
+
+
+class AnsibleExitJson(Exception):
+    pass
+
+
+class AnsibleFailJson(Exception):
+    pass
+
+
+def exit_json(*args, **kwargs):
+    if 'changed' not in kwargs:
+        kwargs['changed'] = False
+    raise AnsibleExitJson(kwargs)
+
+
+def fail_json(*args, **kwargs):
+    kwargs['failed'] = True
+    raise AnsibleFailJson(kwargs)
+
+
+class TestCirconusAnnotation(unittest.TestCase):
+
+    def setUp(self):
+        self.module = circonus_annotation
+
+        self.mock_exit_fail = patch.multiple(basic.AnsibleModule, exit_json=exit_json, fail_json=fail_json)
+        self.mock_exit_fail.start()
+        self.addCleanup(self.mock_exit_fail.stop)
+
+    def tearDown(self):
+        pass
+
+    def test_without_required_parameters(self):
+        """Failure must occurs when all parameters are missing"""
+        with self.assertRaises(AnsibleFailJson):
+            set_module_args({})
+            self.module.main()
+
+    def test_add_annotation(self):
+        """Check that result is changed"""
+        set_module_args({
+            'category': 'test category',
+            'description': 'test description',
+            'title': 'test title',
+            'api_key': str(uuid.uuid4()),
+        })
+
+        cid = '/annotation/100000'
+
+        def send(self, request, stream=False, timeout=None, verify=True, cert=None, proxies=None):
+            data = {
+                '_cid': cid,
+                '_created': 1502146995,
+                '_last_modified': 1502146995,
+                '_last_modified_by': '/user/1000',
+                'category': 'test category',
+                'description': 'test description',
+                'rel_metrics': [],
+                'start': 1502145480,
+                'stop': None,
+                'title': 'test title',
+            }
+            raw = to_bytes(json.dumps(data))
+            resp = HTTPResponse(body=io.BytesIO(raw), preload_content=False)
+            resp.status = 200
+            resp.reason = 'OK'
+            resp.headers = {'X-Circonus-API-Version': '2.00'}
+            return self.build_response(request, resp)
+
+        with patch('requests.adapters.HTTPAdapter.send', autospec=True, side_effect=send) as send:
+            with self.assertRaises(AnsibleExitJson) as result:
+                self.module.main()
+            self.assertTrue(result.exception.args[0]['changed'])
+            self.assertEqual(result.exception.args[0]['annotation']['_cid'], cid)
+        self.assertEqual(send.call_count, 1)
+
+    def test_add_annotation_unicode(self):
+        """Check that result is changed.
+           Note: it seems there is a bug which prevent to create an annotation
+           with a non-ASCII category if this category already exists, in such
+           case an Internal Server Error (500) occurs."""
+        set_module_args({
+            'category': 'new catégorÿ',
+            'description': 'test description',
+            'title': 'test title',
+            'api_key': str(uuid.uuid4()),
+        })
+
+        cid = '/annotation/100000'
+
+        def send(self, request, stream=False, timeout=None, verify=True, cert=None, proxies=None):
+            data = {
+                '_cid': '/annotation/100000',
+                '_created': 1502236928,
+                '_last_modified': 1502236928,
+                '_last_modified_by': '/user/1000',
+                # use res['annotation']['category'].encode('latin1').decode('utf8')
+                'category': u'new cat\xc3\xa9gor\xc3\xbf',
+                'description': 'test description',
+                'rel_metrics': [],
+                'start': 1502236927,
+                'stop': 1502236927,
+                'title': 'test title',
+            }
+
+            raw = to_bytes(json.dumps(data), encoding='latin1')
+            resp = HTTPResponse(body=io.BytesIO(raw), preload_content=False)
+            resp.status = 200
+            resp.reason = 'OK'
+            resp.headers = {'X-Circonus-API-Version': '2.00'}
+            return self.build_response(request, resp)
+
+        with patch('requests.adapters.HTTPAdapter.send', autospec=True, side_effect=send) as send:
+            with self.assertRaises(AnsibleExitJson) as result:
+                self.module.main()
+            self.assertTrue(result.exception.args[0]['changed'])
+            self.assertEqual(result.exception.args[0]['annotation']['_cid'], cid)
+        self.assertEqual(send.call_count, 1)
+
+    def test_auth_failure(self):
+        """Check that an error is raised when authentication failed"""
+        set_module_args({
+            'category': 'test category',
+            'description': 'test description',
+            'title': 'test title',
+            'api_key': str(uuid.uuid4()),
+        })
+
+        cid = '/annotation/100000'
+
+        def send(self, request, stream=False, timeout=None, verify=True, cert=None, proxies=None):
+            data = {
+                '_cid': cid,
+                '_created': 1502146995,
+                '_last_modified': 1502146995,
+                '_last_modified_by': '/user/1000',
+                'category': 'test category',
+                'description': 'test description',
+                'rel_metrics': [],
+                'start': 1502145480,
+                'stop': None,
+                'title': 'test title',
+            }
+            raw = to_bytes(json.dumps(data))
+            resp = HTTPResponse(body=io.BytesIO(raw), preload_content=False)
+            resp.status = 403
+            resp.reason = 'Forbidden'
+            resp.headers = {'X-Circonus-API-Version': '2.00'}
+            return self.build_response(request, resp)
+
+        with patch('requests.adapters.HTTPAdapter.send', autospec=True, side_effect=send) as send:
+            with self.assertRaises(AnsibleFailJson) as result:
+                self.module.main()
+            self.assertTrue(result.exception.args[0]['failed'])
+            self.assertEqual(result.exception.args[0]['reason'].response.status_code, 403)
+        self.assertEqual(send.call_count, 1)