5 files changed, 23 insertions, 3 deletions
diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index bd333da081..3d4cc8fae6 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Add `Array#second_to_last` and `Array#third_to_last` methods.
+
+    *Brian Christian*
+
 *  Fix regression in `Hash#dig` for HashWithIndifferentAccess.
    *Jon Moss*
 
diff --git a/activesupport/lib/active_support/core_ext/array/access.rb b/activesupport/lib/active_support/core_ext/array/access.rb
index 3177d8498e..37d833887a 100644
--- a/activesupport/lib/active_support/core_ext/array/access.rb
+++ b/activesupport/lib/active_support/core_ext/array/access.rb
@@ -73,4 +73,18 @@ class Array
   def forty_two
     self[41]
   end
+
+  # Equal to <tt>self[-3]</tt>.
+  #
+  #   %w( a b c d e ).third_to_last # => "c"
+  def third_to_last
+    self[-3]
+  end
+
+  # Equal to <tt>self[-2]</tt>.
+  #
+  #   %w( a b c d e ).second_to_last # => "d"
+  def second_to_last
+    self[-2]
+  end
 end
diff --git a/activesupport/lib/active_support/deprecation/behaviors.rb b/activesupport/lib/active_support/deprecation/behaviors.rb
index 0de891f1a2..dc24e2d0e1 100644
--- a/activesupport/lib/active_support/deprecation/behaviors.rb
+++ b/activesupport/lib/active_support/deprecation/behaviors.rb
@@ -11,7 +11,7 @@ module ActiveSupport
     DEFAULT_BEHAVIORS = {
       raise: ->(message, callstack) {
         e = DeprecationException.new(message)
-        e.set_backtrace(callstack)
+        e.set_backtrace(callstack.map(&:to_s))
         raise e
       },
 
diff --git a/activesupport/test/core_ext/array/access_test.rb b/activesupport/test/core_ext/array/access_test.rb
index 3f1e0c4cb4..1d834667f0 100644
--- a/activesupport/test/core_ext/array/access_test.rb
+++ b/activesupport/test/core_ext/array/access_test.rb
@@ -26,6 +26,8 @@ class AccessTest < ActiveSupport::TestCase
     assert_equal array[3], array.fourth
     assert_equal array[4], array.fifth
     assert_equal array[41], array.forty_two
+    assert_equal array[-3], array.third_to_last
+    assert_equal array[-2], array.second_to_last
   end
 
   def test_without
diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index 58a0a3964d..45c88b79cb 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -105,13 +105,13 @@ class DeprecationTest < ActiveSupport::TestCase
     ActiveSupport::Deprecation.behavior = :raise
 
     message   = 'Revise this deprecated stuff now!'
-    callstack = %w(foo bar baz)
+    callstack = caller_locations
 
     e = assert_raise ActiveSupport::DeprecationException do
       ActiveSupport::Deprecation.behavior.first.call(message, callstack)
     end
     assert_equal message, e.message
-    assert_equal callstack, e.backtrace
+    assert_equal callstack.map(&:to_s), e.backtrace.map(&:to_s)
   end
 
   def test_default_stderr_behavior