1 files changed, 48 insertions, 0 deletions
diff --git a/activesupport/test/core_ext/module_test.rb b/activesupport/test/core_ext/module_test.rb
index a4d4444d69..e918823074 100644
--- a/activesupport/test/core_ext/module_test.rb
+++ b/activesupport/test/core_ext/module_test.rb
@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require "abstract_unit"
 require "active_support/core_ext/module"
 
@@ -372,6 +374,14 @@ class ModuleTest < ActiveSupport::TestCase
     assert_match(/undefined method `my_fake_method' for/, e.message)
   end
 
+  def test_delegate_missing_to_raises_delegation_error_if_target_nil
+    e = assert_raises(Module::DelegationError) do
+      DecoratedTester.new(nil).name
+    end
+
+    assert_equal "name delegated to client, but client is nil", e.message
+  end
+
   def test_delegate_missing_to_affects_respond_to
     assert DecoratedTester.new(@david).respond_to?(:name)
     assert_not DecoratedTester.new(@david).respond_to?(:private_name)
@@ -392,4 +402,42 @@ class ModuleTest < ActiveSupport::TestCase
     event = Event.new(Tester.new)
     assert_equal 1, event.foo
   end
+
+  def test_private_delegate
+    location = Class.new do
+      def initialize(place)
+        @place = place
+      end
+
+      private(*delegate(:street, :city, to: :@place))
+    end
+
+    place = location.new(Somewhere.new("Such street", "Sad city"))
+
+    assert_not place.respond_to?(:street)
+    assert_not place.respond_to?(:city)
+
+    assert place.respond_to?(:street, true) # Asking for private method
+    assert place.respond_to?(:city, true)
+  end
+
+  def test_private_delegate_prefixed
+    location = Class.new do
+      def initialize(place)
+        @place = place
+      end
+
+      private(*delegate(:street, :city, to: :@place, prefix: :the))
+    end
+
+    place = location.new(Somewhere.new("Such street", "Sad city"))
+
+    assert_not place.respond_to?(:street)
+    assert_not place.respond_to?(:city)
+
+    assert_not place.respond_to?(:the_street)
+    assert place.respond_to?(:the_street, true)
+    assert_not place.respond_to?(:the_city)
+    assert place.respond_to?(:the_city, true)
+  end
 end