diff --git a/test/entity_test.rb b/test/entity_test.rb
index <HASH>..<HASH> 100644
--- a/test/entity_test.rb
+++ b/test/entity_test.rb
@@ -91,6 +91,13 @@ module XCDM
                       "Author", inverseName: "article", inverseEntity: "Author" }], e.relationships
     end
 
+    def test_has_one_should_not_plural
+      e.has_one 'address'
+      assert_equal [{ optional: "YES", deletionRule: "Nullify", syncable: "YES",
+                      name: "address", minCount: "1", maxCount: "1", destinationEntity:
+                      "Address", inverseName: "article", inverseEntity: "Address" }], e.relationships
+    end
+
     def test_belongs_to
       e.belongs_to 'author'
       assert_equal [{ optional: "YES", deletionRule: "Nullify", syncable: "YES",
Added test for entities that end  's' and has_one

The reason for this test is that release <I> has a bug where if you an
entity with the name 'Address' and another entity 'has_one :address',
the relationship is not properly handled.

In other words, if you run this test for verson <I>, it fails. On
master, it succeeds. So this test is simply to prevent regression.

I believe the fix to this was simply when the code updated the version
of ActiveSupport.