diff --git a/src/djangooidc/tests/test_backends.py b/src/djangooidc/tests/test_backends.py
new file mode 100644
index 000000000..3283e2cc4
--- /dev/null
+++ b/src/djangooidc/tests/test_backends.py
@@ -0,0 +1,82 @@
+from django.test import TestCase
+from django.contrib.auth import get_user_model
+from django.utils import timezone
+from registrar.models import User
+from ..backends import OpenIdConnectBackend  # Adjust the import path based on your project structure
+
+class OpenIdConnectBackendTestCase(TestCase):
+
+    def setUp(self):
+        self.backend = OpenIdConnectBackend()
+        self.kwargs = {
+            "sub": "test_user",
+            "given_name": "John",
+            "family_name": "Doe",
+            "email": "john.doe@example.com",
+            "phone": "123456789",
+        }
+
+    def tearDown(self) -> None:
+        User.objects.all().delete()
+
+    def test_authenticate_with_create_user(self):
+        """Test that authenticate creates a new user if it does not find
+        existing user"""
+        # Ensure that the authenticate method creates a new user
+        user = self.backend.authenticate(request=None, **self.kwargs)
+        self.assertIsNotNone(user)
+        self.assertIsInstance(user, User)
+        self.assertEqual(user.username, "test_user")
+
+        # Verify that user fields are correctly set
+        self.assertEqual(user.first_name, "John")
+        self.assertEqual(user.last_name, "Doe")
+        self.assertEqual(user.email, "john.doe@example.com")
+        self.assertEqual(user.phone, "123456789")
+
+    def test_authenticate_with_existing_user(self):
+        """Test that authenticate updates an existing user if it finds one.
+        For this test, given_name and family_name are supplied"""
+        # Create an existing user with the same username
+        existing_user = User.objects.create_user(username="test_user")
+
+        # Ensure that the authenticate method updates the existing user
+        user = self.backend.authenticate(request=None, **self.kwargs)
+        self.assertIsNotNone(user)
+        self.assertIsInstance(user, User)
+        self.assertEqual(user, existing_user)  # The same user instance should be returned
+
+        # Verify that user fields are correctly updated
+        self.assertEqual(user.first_name, "John")
+        self.assertEqual(user.last_name, "Doe")
+        self.assertEqual(user.email, "john.doe@example.com")
+        self.assertEqual(user.phone, "123456789")
+
+    def test_authenticate_with_existing_user_no_name(self):
+        """Test that authenticate updates an existing user if it finds one.
+        For this test, given_name and family_name are supplied"""
+        # Create an existing user with the same username and with first and last names
+        existing_user = User.objects.create_user(username="test_user",first_name="John",last_name="Doe")
+
+        # Remove given_name and family_name from the input, self.kwargs
+        self.kwargs.pop("given_name", None) 
+        self.kwargs.pop("family_name", None)
+
+        # Ensure that the authenticate method updates the existing user
+        # and preserves existing first and last names
+        user = self.backend.authenticate(request=None, **self.kwargs)
+        self.assertIsNotNone(user)
+        self.assertIsInstance(user, User)
+        self.assertEqual(user, existing_user)  # The same user instance should be returned
+
+        # Verify that user fields are correctly updated
+        self.assertEqual(user.first_name, "John")
+        self.assertEqual(user.last_name, "Doe")
+        self.assertEqual(user.email, "john.doe@example.com")
+        self.assertEqual(user.phone, "123456789")
+
+    def test_authenticate_with_unknown_user(self):
+        """Test that authenticate returns None when no kwargs are supplied"""
+        # Ensure that the authenticate method handles the case when the user is not found
+        user = self.backend.authenticate(request=None, **{})
+        self.assertIsNone(user)