feat: Use email as fallback for User.full_name

Author: sman591

app/models/user.rb

@@ -56,7 +56,7 @@ def last_name
   end
 
   def full_name
-    return "" if questionnaire.blank?
+    return email if questionnaire.blank?
     questionnaire.full_name
   end
 

test/models/user_test.rb

@@ -48,9 +48,9 @@ class UserTest < ActiveSupport::TestCase
       assert_equal "Alpha Beta", questionnaire.user.full_name
     end
 
-    should "return blank when no questionnaire exists" do
-      user = create(:user)
-      assert_equal "", user.full_name
+    should "return email when no questionnaire exists" do
+      user = create(:user, email: "foo@example.com")
+      assert_equal "foo@example.com", user.full_name
     end
   end