1 files changed, 10 insertions, 0 deletions
diff --git a/activemodel/test/cases/conversion_test.rb b/activemodel/test/cases/conversion_test.rb
index 3bb177591d..c5cfbf909d 100644
--- a/activemodel/test/cases/conversion_test.rb
+++ b/activemodel/test/cases/conversion_test.rb
@@ -24,6 +24,16 @@ class ConversionTest < ActiveModel::TestCase
     assert_equal "1", Contact.new(id: 1).to_param
   end
 
+  test "to_param returns nil if to_key is nil" do
+    klass = Class.new(Contact) do
+      def persisted?
+        true
+      end
+    end
+
+    assert_nil klass.new.to_param
+  end
+
   test "to_partial_path default implementation returns a string giving a relative path" do
     assert_equal "contacts/contact", Contact.new.to_partial_path
     assert_equal "helicopters/helicopter", Helicopter.new.to_partial_path,