Convert spec to test

#746

test/models/contact/contact_test.rb

@@ -12,4 +12,18 @@ class ContactTest < ActiveSupport::TestCase
   def test_invalid_fixture_is_invalid
     assert contacts(:invalid).invalid?
   end
+
+  def test_in_use_if_acts_as_a_registrant
+    DomainContact.delete_all
+    assert @contact.used?
+  end
+
+  def test_in_use_if_acts_as_a_domain_contact
+    Domain.update_all(registrant_id: contacts(:william))
+    assert @contact.used?
+  end
+
+  def test_not_in_use_if_acts_as_neither_registrant_nor_domain_contact
+    refute contacts(:not_in_use).used?
+  end
 end