From 7c67b949869366bf82805f42e38a0bb1757eaadc Mon Sep 17 00:00:00 2001
From: Ryuta Kamizono <kamipo@gmail.com>
Date: Mon, 22 Mar 2021 15:20:50 +0900
Subject: [PATCH] Make infinity handling symmetrical in cast and deserialize

Related: #41716, 30391e9ddba745d6bdc0b23f526ecf432dfe6adf.
---
 .../active_record/attribute_methods/time_zone_conversion.rb | 6 +++---
 .../test/cases/adapters/postgresql/infinity_test.rb         | 4 ++++
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
index 0423c7bf06..3eed7afd3e 100644
--- a/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
+++ b/activerecord/lib/active_record/attribute_methods/time_zone_conversion.rb
@@ -19,14 +19,14 @@ def cast(value)
 
           if value.is_a?(Hash)
             set_time_zone_without_conversion(super)
-          elsif value == ::Float::INFINITY || value == -::Float::INFINITY
-            value
           elsif value.respond_to?(:in_time_zone)
             begin
               super(user_input_in_time_zone(value)) || super
             rescue ArgumentError
               nil
             end
+          elsif value.respond_to?(:infinite?) && value.infinite?
+            value
           else
             map_avoiding_infinite_recursion(super) { |v| cast(v) }
           end
@@ -38,7 +38,7 @@ def convert_time_to_time_zone(value)
 
             if value.acts_like?(:time)
               value.in_time_zone
-            elsif value.is_a?(::Float)
+            elsif value.respond_to?(:infinite?) && value.infinite?
               value
             else
               map_avoiding_infinite_recursion(value) { |v| convert_time_to_time_zone(v) }
diff --git a/activerecord/test/cases/adapters/postgresql/infinity_test.rb b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
index 968c016d47..d599683f2a 100644
--- a/activerecord/test/cases/adapters/postgresql/infinity_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/infinity_test.rb
@@ -82,6 +82,10 @@ class PostgresqlInfinity < ActiveRecord::Base
       record = PostgresqlInfinity.create!(datetime: Float::INFINITY)
       assert_equal Float::INFINITY, record.datetime
       assert_equal record.datetime, record.reload.datetime
+
+      record = PostgresqlInfinity.create!(datetime: BigDecimal::INFINITY)
+      assert_equal Float::INFINITY, record.datetime
+      assert_equal record.datetime, record.reload.datetime
     end
   ensure
     # setting time_zone_aware_attributes causes the types to change.