Add AS::Deprecation::DeprecatedConstantAccessor

An alternative to DeprecatedConstantProxy which works more transparently
with exceptions because it returns the object that the new constant
refers to rather than a proxy. This is then compatible with
`rescue OldException`.

1 files changed, 23 insertions, 0 deletions

diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index 5f72fbf662..36d1ef0849 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -35,6 +35,18 @@ class Deprecatee
   A = ActiveSupport::Deprecation::DeprecatedConstantProxy.new("Deprecatee::A", "Deprecatee::B::C")
 end
 
+class DeprecateeWithAccessor
+  include ActiveSupport::Deprecation::DeprecatedConstantAccessor
+
+  module B
+    C = 1
+  end
+  deprecate_constant "A", "DeprecateeWithAccessor::B::C"
+
+  class NewException < StandardError; end
+  deprecate_constant "OldException", "DeprecateeWithAccessor::NewException"
+end
+
 class DeprecationTest < ActiveSupport::TestCase
   include ActiveSupport::Testing::Stream
 
@@ -162,6 +174,17 @@ class DeprecationTest < ActiveSupport::TestCase
     assert_not_deprecated { assert_equal Deprecatee::B::C.class, Deprecatee::A.class }
   end
 
+  def test_deprecated_constant_accessor
+    assert_not_deprecated { DeprecateeWithAccessor::B::C }
+    assert_deprecated("DeprecateeWithAccessor::A") { assert_equal DeprecateeWithAccessor::B::C, DeprecateeWithAccessor::A }
+  end
+
+  def test_deprecated_constant_accessor_exception
+    raise DeprecateeWithAccessor::NewException.new("Test")
+  rescue DeprecateeWithAccessor::OldException => e
+    assert_kind_of DeprecateeWithAccessor::NewException, e
+  end
+
   def test_assert_deprecated_raises_when_method_not_deprecated
     assert_raises(Minitest::Assertion) { assert_deprecated { @dtc.not } }
   end