Print the proper ::Float::INFINITY value when used as a default value

Addresses https://github.com/rails/rails/issues/22396

3 files changed, 24 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/type/float.rb b/activemodel/lib/active_model/type/float.rb
index 0f925bc7e1..4c128eea01 100644
--- a/activemodel/lib/active_model/type/float.rb
+++ b/activemodel/lib/active_model/type/float.rb
@@ -7,6 +7,15 @@ module ActiveModel
         :float
       end
 
+      def type_cast_for_schema(value)
+        return "::Float::NAN" if value.try(:nan?)
+        case value
+        when ::Float::INFINITY then "::Float::INFINITY"
+        when -::Float::INFINITY then "-::Float::INFINITY"
+        else super
+        end
+      end
+
       alias serialize cast
 
       private
diff --git a/activerecord/test/cases/schema_dumper_test.rb b/activerecord/test/cases/schema_dumper_test.rb
index f1927f561e..8bf7cf6b96 100644
--- a/activerecord/test/cases/schema_dumper_test.rb
+++ b/activerecord/test/cases/schema_dumper_test.rb
@@ -425,6 +425,13 @@ class SchemaDumperDefaultsTest < ActiveRecord::TestCase
       t.datetime :datetime_with_default, default: "2014-06-05 07:17:04"
       t.time     :time_with_default,     default: "07:17:04"
     end
+
+    if current_adapter?(:PostgreSQLAdapter)
+      @connection.create_table :infinity_defaults, force: true do |t|
+        t.float    :float_with_inf_default,    default: Float::INFINITY
+        t.float    :float_with_nan_default,    default: Float::NAN
+      end
+    end
   end
 
   teardown do
@@ -440,4 +447,11 @@ class SchemaDumperDefaultsTest < ActiveRecord::TestCase
     assert_match %r{t\.datetime\s+"datetime_with_default",\s+default: '2014-06-05 07:17:04'}, output
     assert_match %r{t\.time\s+"time_with_default",\s+default: '2000-01-01 07:17:04'}, output
   end
+
+  def test_schema_dump_with_float_column_infinity_default
+    skip unless current_adapter?(:PostgreSQLAdapter)
+    output = dump_table_schema('infinity_defaults')
+    assert_match %r{t\.float\s+"float_with_inf_default",\s+default: ::Float::INFINITY}, output
+    assert_match %r{t\.float\s+"float_with_nan_default",\s+default: ::Float::NAN}, output
+  end
 end
diff --git a/activerecord/test/cases/type/date_time_test.rb b/activerecord/test/cases/type/date_time_test.rb
index bc4900e1c2..6848619ece 100644
--- a/activerecord/test/cases/type/date_time_test.rb
+++ b/activerecord/test/cases/type/date_time_test.rb
@@ -3,7 +3,7 @@ require "models/task"
 
 module ActiveRecord
   module Type
-    class IntegerTest < ActiveRecord::TestCase
+    class DateTimeTest < ActiveRecord::TestCase
       def test_datetime_seconds_precision_applied_to_timestamp
         skip "This test is invalid if subsecond precision isn't supported" unless subsecond_precision_supported?
         p = Task.create!(starting: ::Time.now)