Handle `FrozenError` if it is available

This pull request handles `FrozenError` introduced by Ruby 2.5.
Refer https://bugs.ruby-lang.org/projects/ruby-trunk/repository/revisions/61131

Since `FrozenError` is a subclass of `RuntimeError` minitest used by master
branch can handle it, though it would be better to handle `FrozenError`
explicitly if possible.

`FrozenError` does not exist in Ruby 2.4 or lower, `frozen_error_class`
handles which exception is expected to be raised.

This pull request is intended to be merged to master,
then backported to `5-1-stable` to address #31508

activerecord/test/cases/aggregations_test.rb

@@ -27,7 +27,7 @@ class AggregationsTest < ActiveRecord::TestCase
 
   def test_immutable_value_objects
     customers(:david).balance = Money.new(100)
-    assert_raise(RuntimeError) { customers(:david).balance.instance_eval { @amount = 20 } }
+    assert_raise(frozen_error_class) { customers(:david).balance.instance_eval { @amount = 20 } }
   end
 
   def test_inferred_mapping

activerecord/test/cases/query_cache_test.rb

@@ -283,7 +283,7 @@ class QueryCacheTest < ActiveRecord::TestCase
       payload[:sql].downcase!
     end
 
-    assert_raises RuntimeError do
+    assert_raises frozen_error_class do
       ActiveRecord::Base.cache do
         assert_queries(1) { Task.find(1); Task.find(1) }
       end

activerecord/test/cases/test_case.rb

@@ -77,6 +77,10 @@ module ActiveRecord
       model.reset_column_information
       model.column_names.include?(column_name.to_s)
     end
+
+    def frozen_error_class
+      Object.const_defined?(:FrozenError) ? FrozenError : RuntimeError
+    end
   end
 
   class PostgreSQLTestCase < TestCase

activerecord/test/cases/transactions_test.rb

@@ -576,7 +576,7 @@ class TransactionTest < ActiveRecord::TestCase
   def test_rollback_when_saving_a_frozen_record
     topic = Topic.new(title: "test")
     topic.freeze
-    e = assert_raise(RuntimeError) { topic.save }
+    e = assert_raise(frozen_error_class) { topic.save }
     # Not good enough, but we can't do much
     # about it since there is no specific error
     # for frozen objects.

activesupport/test/abstract_unit.rb

@@ -38,4 +38,8 @@ class ActiveSupport::TestCase
   private def jruby_skip(message = "")
     skip message if defined?(JRUBY_VERSION)
   end
+
+  def frozen_error_class
+    Object.const_defined?(:FrozenError) ? FrozenError : RuntimeError
+  end
 end

activesupport/test/core_ext/hash_ext_test.rb

@@ -446,7 +446,7 @@ class HashExtTest < ActiveSupport::TestCase
     original.freeze
     assert_nothing_raised { original.except(:a) }
 
-    assert_raise(RuntimeError) { original.except!(:a) }
+    assert_raise(frozen_error_class) { original.except!(:a) }
   end
 
   def test_except_does_not_delete_values_in_original

railties/test/application/middleware_test.rb

@@ -249,7 +249,7 @@ module ApplicationTests
 
     test "can't change middleware after it's built" do
       boot!
-      assert_raise RuntimeError do
+      assert_raise frozen_error_class do
         app.config.middleware.use Rack::Config
       end
     end

railties/test/isolation/abstract_unit.rb

@@ -406,6 +406,10 @@ class ActiveSupport::TestCase
   include TestHelpers::Rack
   include TestHelpers::Generation
   include ActiveSupport::Testing::Stream
+
+  def frozen_error_class
+    Object.const_defined?(:FrozenError) ? FrozenError : RuntimeError
+  end
 end
 
 # Create a scope and build a fixture rails app