Introducing DateTime #utc, #utc? and #utc_offset, for duck-typing...

Introducing DateTime #utc, #utc? and #utc_offset, for duck-typing compatibility with Time. Closes #10002

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8649 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/CHANGELOG

 *SVN*
 
+* Introducing DateTime #utc, #utc? and #utc_offset, for duck-typing compatibility with Time. Closes #10002 [Geoff Buesing]
+
 * Time#to_json uses Numeric#to_utc_offset_s to output a cross-platform-consistent representation without having to convert to DateTime. References #9750 [Geoff Buesing]
 
 * Refactor number-to-HH:MM-string conversion logic from TimeZone#formatted_offset to a reusable Numeric#to_utc_offset_s method. [Geoff Buesing]

activesupport/lib/active_support/core_ext/date_time/calculations.rb

@@ -71,6 +71,26 @@ def beginning_of_day
         def end_of_day
           change(:hour => 23, :min => 59, :sec => 59)
         end
+        
+        # Adjusts DateTime to UTC by adding its offset value; offset is set to 0
+        #
+        # Example:
+        #
+        #   DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(-6, 24))       # => Mon, 21 Feb 2005 10:11:12 -0600
+        #   DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(-6, 24)).utc   # => Mon, 21 Feb 2005 16:11:12 +0000
+        def utc
+          new_offset(0)
+        end
+        
+        # Returns true if offset == 0
+        def utc?
+          offset == 0
+        end
+        
+        # Returns the offset value in seconds
+        def utc_offset
+          (offset * 86400).to_i
+        end
       end
     end
   end

activesupport/test/core_ext/date_time_ext_test.rb

@@ -219,6 +219,28 @@ def test_local_offset
       assert_equal Rational(-6, 24), DateTime.local_offset
     end
   end
+  
+  def test_utc?
+    assert_equal true, DateTime.civil(2005, 2, 21, 10, 11, 12).utc?
+    assert_equal true, DateTime.civil(2005, 2, 21, 10, 11, 12, 0).utc?
+    assert_equal false, DateTime.civil(2005, 2, 21, 10, 11, 12, 0.25).utc?
+    assert_equal false, DateTime.civil(2005, 2, 21, 10, 11, 12, -0.25).utc?
+  end
+  
+  def test_utc_offset
+    assert_equal 0, DateTime.civil(2005, 2, 21, 10, 11, 12).utc_offset
+    assert_equal 0, DateTime.civil(2005, 2, 21, 10, 11, 12, 0).utc_offset
+    assert_equal 21600, DateTime.civil(2005, 2, 21, 10, 11, 12, 0.25).utc_offset
+    assert_equal( -21600, DateTime.civil(2005, 2, 21, 10, 11, 12, -0.25).utc_offset )
+    assert_equal( -18000, DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(-5, 24)).utc_offset )
+  end
+  
+  def test_utc
+    assert_equal DateTime.civil(2005, 2, 21, 16, 11, 12, 0), DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(-6, 24)).utc
+    assert_equal DateTime.civil(2005, 2, 21, 15, 11, 12, 0), DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(-5, 24)).utc
+    assert_equal DateTime.civil(2005, 2, 21, 10, 11, 12, 0), DateTime.civil(2005, 2, 21, 10, 11, 12, 0).utc
+    assert_equal DateTime.civil(2005, 2, 21, 9, 11, 12, 0), DateTime.civil(2005, 2, 21, 10, 11, 12, Rational(1, 24)).utc
+  end
 
   protected
     def with_timezone(new_tz = 'US/Eastern')