diff --git a/tcms/utils/tests/test_github.py b/tcms/utils/tests/test_github.py
index 82716ae23f..d79f94b633 100644
--- a/tcms/utils/tests/test_github.py
+++ b/tcms/utils/tests/test_github.py
@@ -1,5 +1,8 @@
 # Copyright (c) 2019 Alexander Todorov <atodorov@MrSenko.com>
 
+import hmac
+import hashlib
+
 from http import HTTPStatus
 
 from django import test
@@ -8,6 +11,19 @@
 from tcms.utils import github
 
 
+class CalculateSignatureTestCase(test.TestCase):
+    def test_string_arguments(self):
+        with self.assertRaisesRegex(TypeError, 'key: expected bytes or bytearray, but got \'str\''):
+            github.calculate_signature('secret', 'content')
+
+    def test_return_format(self):
+        sha1 = hmac.new(key=b'secret',
+                        msg=b'content',
+                        digestmod=hashlib.sha1).hexdigest()
+        self.assertEqual(github.calculate_signature(b'secret', b'content'),
+                         f'sha1={sha1}')
+
+
 class VerifySignatureTestCase(test.TestCase):
     def setUp(self):
         self.factory = test.RequestFactory()
@@ -27,3 +43,13 @@ def test_invalid_signature_header(self):
 
         self.assertIsInstance(result, HttpResponseForbidden)
         self.assertEqual(HTTPStatus.FORBIDDEN, result.status_code)
+
+    def test_valid_signature_header(self):
+        request = self.factory.post(self.url)
+        sha1 = hmac.new(key=b'secret',
+                        msg=request.body,
+                        digestmod=hashlib.sha1).hexdigest()
+        request.META['HTTP_X_HUB_SIGNATURE'] = f'sha1={sha1}'
+        result = github.verify_signature(request, b'secret')
+        self.assertIsInstance(result, bool)
+        self.assertTrue(result)