Override Time.at to work with Time-like values

Time.at allows passing a single Time argument which is then converted
to an integer. The conversion code since 1.9.3r429 explicitly checks
for an instance of Time so we need to override it to allow DateTime
and ActiveSupport::TimeWithZone values.

3 files changed, 38 insertions, 0 deletions

diff --git a/activesupport/CHANGELOG.md b/activesupport/CHANGELOG.md
index 7f2acb2f65..d612c644af 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,5 +1,9 @@
 ## unreleased ##
 
+*   Override `Time.at` to support the passing of Time-like values when called with a single argument.
+
+    *Andrew White*
+
 *   Revert the changes on unicode character encoding from `ActiveSupport::JSON.encode`.
     This was causing a regression where the resulting string is always returning UTF-8.
     Also it changes the behavior of this method on a stable release.
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index 9146d82bd8..7524063efb 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -45,6 +45,18 @@ class Time
     def current
       ::Time.zone ? ::Time.zone.now : ::Time.now
     end
+
+    # Layers additional behavior on Time.at so that ActiveSupport::TimeWithZone and DateTime
+    # instances can be used when called with a single argument
+    def at_with_coercion(*args)
+      if args.size == 1 && args.first.acts_like?(:time)
+        at_without_coercion(args.first.to_i)
+      else
+        at_without_coercion(*args)
+      end
+    end
+    alias_method :at_without_coercion, :at
+    alias_method :at, :at_with_coercion
   end
 
   # Tells whether the Time object's time lies in the past
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 0d680832ef..a22e161279 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -774,6 +774,28 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal(-1, Time.utc(2000) <=> ActiveSupport::TimeWithZone.new( Time.utc(2000, 1, 1, 0, 0, 1), ActiveSupport::TimeZone['UTC'] ))
   end
 
+  def test_at_with_datetime
+    assert_equal Time.utc(2000, 1, 1, 0, 0, 0), Time.at(DateTime.civil(2000, 1, 1, 0, 0, 0))
+
+    # Only test this if the underlying Time.at raises a TypeError
+    begin
+      Time.at_without_coercion(Time.now, 0)
+    rescue TypeError
+      assert_raise(TypeError) { assert_equal(Time.utc(2000, 1, 1, 0, 0, 0), Time.at(DateTime.civil(2000, 1, 1, 0, 0, 0), 0)) }
+    end
+  end
+
+  def test_at_with_time_with_zone
+    assert_equal Time.utc(2000, 1, 1, 0, 0, 0), Time.at(ActiveSupport::TimeWithZone.new(Time.utc(2000, 1, 1, 0, 0, 0), ActiveSupport::TimeZone['UTC']))
+
+    # Only test this if the underlying Time.at raises a TypeError
+    begin
+      Time.at_without_coercion(Time.now, 0)
+    rescue TypeError
+      assert_raise(TypeError) { assert_equal(Time.utc(2000, 1, 1, 0, 0, 0), Time.at(ActiveSupport::TimeWithZone.new(Time.utc(2000, 1, 1, 0, 0, 0), ActiveSupport::TimeZone['UTC']), 0)) }
+    end
+  end
+
   def test_eql?
     assert_equal true, Time.utc(2000).eql?( ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone['UTC']) )
     assert_equal true, Time.utc(2000).eql?( ActiveSupport::TimeWithZone.new(Time.utc(2000), ActiveSupport::TimeZone["Hawaii"]) )