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 ae3fd811b3..5a1c14683e 100644
--- a/activesupport/CHANGELOG.md
+++ b/activesupport/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Override `Time.at` to support the passing of Time-like values when called with a single argument.
+
+    *Andrew White*
+
 *   Prevent side effects to hashes inside arrays when
     `Hash#with_indifferent_access` is called.
     Fixes #10526
diff --git a/activesupport/lib/active_support/core_ext/time/calculations.rb b/activesupport/lib/active_support/core_ext/time/calculations.rb
index a3ce7dbe3f..c65f20c2d5 100644
--- a/activesupport/lib/active_support/core_ext/time/calculations.rb
+++ b/activesupport/lib/active_support/core_ext/time/calculations.rb
@@ -65,6 +65,18 @@ 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
 
   # Seconds since midnight: Time.now.seconds_since_midnight
diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 4e53aff00b..eefcdbb1b3 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -741,6 +741,28 @@ 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"]) )