diff --git a/activesupport/test/core_ext/date_ext_test.rb b/activesupport/test/core_ext/date_ext_test.rb
index ea93663329..0612e67079 100644
--- a/activesupport/test/core_ext/date_ext_test.rb
+++ b/activesupport/test/core_ext/date_ext_test.rb
@@ -28,6 +28,7 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
     assert_equal "February 21, 2005",   date.to_s(:long)
     assert_equal "February 21st, 2005", date.to_s(:long_ordinal)
     assert_equal "2005-02-21",          date.to_s(:db)
+    assert_equal "2005-02-21",          date.to_s(:inspect)
     assert_equal "21 Feb 2005",         date.to_s(:rfc822)
     assert_equal "2005-02-21",          date.to_s(:iso8601)
   end
@@ -39,6 +40,7 @@ class DateExtCalculationsTest < ActiveSupport::TestCase
     assert_equal "February 01, 2005",   date.to_s(:long)
     assert_equal "February 1st, 2005",  date.to_s(:long_ordinal)
     assert_equal "2005-02-01",          date.to_s(:db)
+    assert_equal "2005-02-01",          date.to_s(:inspect)
     assert_equal "01 Feb 2005",         date.to_s(:rfc822)
     assert_equal "2005-02-01",          date.to_s(:iso8601)
   end
diff --git a/activesupport/test/core_ext/date_time_ext_test.rb b/activesupport/test/core_ext/date_time_ext_test.rb
index 2a1c33692b..2c6ad8d866 100644
--- a/activesupport/test/core_ext/date_time_ext_test.rb
+++ b/activesupport/test/core_ext/date_time_ext_test.rb
@@ -15,13 +15,14 @@ class DateTimeExtCalculationsTest < ActiveSupport::TestCase
 
   def test_to_s
     datetime = DateTime.new(2005, 2, 21, 14, 30, 0, 0)
-    assert_equal "2005-02-21 14:30:00",               datetime.to_s(:db)
-    assert_equal "14:30",                             datetime.to_s(:time)
-    assert_equal "21 Feb 14:30",                      datetime.to_s(:short)
-    assert_equal "February 21, 2005 14:30",           datetime.to_s(:long)
-    assert_equal "Mon, 21 Feb 2005 14:30:00 +0000",   datetime.to_s(:rfc822)
-    assert_equal "February 21st, 2005 14:30",         datetime.to_s(:long_ordinal)
-    assert_match(/^2005-02-21T14:30:00(Z|\+00:00)$/,  datetime.to_s)
+    assert_equal "2005-02-21 14:30:00",                 datetime.to_s(:db)
+    assert_equal "2005-02-21 14:30:00.000000000 +0000", datetime.to_s(:inspect)
+    assert_equal "14:30",                               datetime.to_s(:time)
+    assert_equal "21 Feb 14:30",                        datetime.to_s(:short)
+    assert_equal "February 21, 2005 14:30",             datetime.to_s(:long)
+    assert_equal "Mon, 21 Feb 2005 14:30:00 +0000",     datetime.to_s(:rfc822)
+    assert_equal "February 21st, 2005 14:30",           datetime.to_s(:long_ordinal)
+    assert_match(/^2005-02-21T14:30:00(Z|\+00:00)$/,    datetime.to_s)
 
     with_env_tz "US/Central" do
       assert_equal "2009-02-05T14:30:05-06:00", DateTime.civil(2009, 2, 5, 14, 30, 5, Rational(-21600, 86400)).to_s(:iso8601)
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 621a46022c..efb185babc 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -562,6 +562,7 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal "February 21st, 2005 17:44",       time.to_s(:long_ordinal)
     with_env_tz "UTC" do
       assert_equal "Mon, 21 Feb 2005 17:44:30 +0000", time.to_s(:rfc822)
+      assert_equal "2005-02-21 17:44:30.123456789 +0000", time.to_s(:inspect)
     end
     with_env_tz "US/Central" do
       assert_equal "Thu, 05 Feb 2009 14:30:05 -0600", Time.local(2009, 2, 5, 14, 30, 5).to_s(:rfc822)
@@ -569,6 +570,8 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
       assert_equal "2009-02-05T14:30:05-06:00", Time.local(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
       assert_equal "2008-06-09T04:05:01-05:00", Time.local(2008, 6, 9, 4, 5, 1).to_s(:iso8601)
       assert_equal "2009-02-05T14:30:05Z", Time.utc(2009, 2, 5, 14, 30, 5).to_s(:iso8601)
+      assert_equal "2009-02-05 14:30:05.000000000 -0600", Time.local(2009, 2, 5, 14, 30, 5).to_s(:inspect)
+      assert_equal "2008-06-09 04:05:01.000000000 -0500", Time.local(2008, 6, 9, 4, 5, 1).to_s(:inspect)
     end
   end
 
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 52b9cc9ecc..eec9af5807 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -141,6 +141,10 @@ class TimeWithZoneTest < ActiveSupport::TestCase
     assert_equal "2000-01-01 00:00:00", @twz.to_s(:db)
   end
 
+  def test_to_s_inspect
+    assert_equal "1999-12-31 19:00:00.000000000 -0500", @twz.to_s(:inspect)
+  end
+
   def test_xmlschema
     assert_equal "1999-12-31T19:00:00-05:00", @twz.xmlschema
   end