diff --git a/validations_common/tests/callback_plugins/test_http_json.py b/validations_common/tests/callback_plugins/test_http_json.py
index ff22712..58acfd8 100644
--- a/validations_common/tests/callback_plugins/test_http_json.py
+++ b/validations_common/tests/callback_plugins/test_http_json.py
@@ -24,14 +24,77 @@ try:
 except ImportError:
     import mock
 
+import re
+
 from validations_common.tests import base
 from validations_common.tests import fakes
 
-import validations_common.library.reportentry as validation
+from ansible.plugins.callback import CallbackBase
+
 from validations_common.callback_plugins import http_json
 
 
+def is_iso_time(time_string):
+    """
+    Checks if string represents valid time in ISO format,
+    with the default delimiter.
+    Regex is somewhat convoluted, but general enough to last
+    at least until the 9999 AD.
+
+    Returns:
+        True if string matches the pattern.
+        False otherwise.
+    """
+    match = re.match(
+        r'\d{4}-[01][0-9]-[0-3][0-9]T[0-3][0-9](:[0-5][0-9]){2}\.\d+Z',
+        time_string)
+
+    if match:
+        return True
+    else:
+        return False
+
+
 class TestHttpJson(base.TestCase):
 
     def setUp(self):
         super(TestHttpJson, self).setUp()
+
+    def test_callback_instantiation(self):
+        """
+        Verifying that the CallbackModule is instantiated properly.
+        Test checks presence of CallbackBase in the inheritance chain,
+        in order to ensure that folowing tests are performed with
+        the correct assumptions.
+        """
+        callback = http_json.CallbackModule()
+
+        self.assertEqual(type(callback).__mro__[2], CallbackBase)
+
+        """
+        Every ansible callback needs to define variable with name and version.
+        """
+        self.assertIn('CALLBACK_NAME', dir(callback))
+        self.assertIn('CALLBACK_VERSION', dir(callback))
+        self.assertIn('CALLBACK_TYPE', dir(callback))
+
+        self.assertEqual(callback.CALLBACK_NAME, 'http_json')
+
+        self.assertIsInstance(callback.CALLBACK_VERSION, float)
+
+        self.assertEqual(callback.CALLBACK_TYPE, 'aggregate')
+
+        """
+        Additionally, the 'http_json' callback performs several
+        other operations during instantiation.
+        """
+
+        self.assertEqual(callback.env, {})
+        self.assertIsNone(callback.t0)
+        """
+        Callback time sanity check only verifies general format
+        of the stored time to be  iso format `YYYY-MM-DD HH:MM:SS.mmmmmm`
+        with 'T' as a separator.
+        For example: '2020-07-03T13:28:21.224103Z'
+        """
+        self.assertTrue(is_iso_time(callback.current_time))