functional auth backend; new get_user() method in authentication model & new accompanying test methods

src/apps/lyric/tests/test_authentication.py

@@ -42,3 +42,15 @@ class AuthenticateTest(TestCase):
         token = Token.objects.create(email="a@b.cde")
         fetched = Token.objects.get(pk=token.uid)
         self.assertEqual(fetched, token)
+
+class GetUserTest(TestCase):
+    def test_gets_user_by_uuid(self):
+        User.objects.create(email="fantaman@example.com")
+        desired_user = User.objects.create(email="discoman@example.com")
+        found_user = PasswordlessAuthenticationBackend().get_user("discoman@example.com")
+        self.assertEqual(found_user, desired_user)
+
+    def test_returns_None_if_no_user_with_that_email(self):
+        self.assertIsNone(
+            PasswordlessAuthenticationBackend().get_user("discoman@example.com")
+        )