[ruby/date] Support -Float::INFINITY...date ranges

Fixes Ruby Bug 12961

https://github.com/ruby/date/commit/7f533c2552

ext/date/lib/date.rb

@@ -5,6 +5,10 @@ require 'date_core'
 
 class Date
 
+  def infinite?
+    false
+  end
+
   class Infinity < Numeric # :nodoc:
 
     include Comparable

test/date/test_date.rb

@@ -6,6 +6,19 @@ class DateSub < Date; end
 class DateTimeSub < DateTime; end
 
 class TestDate < Test::Unit::TestCase
+  def test_range_infinite_float
+    today = Date.today
+    r = today...Float::INFINITY
+    assert_equal today, r.begin
+    assert_equal Float::INFINITY, r.end
+    assert_equal true, r.cover?(today+1)
+    assert_equal false, r.cover?(today-1)
+    r = (-Float::INFINITY)...today
+    assert_equal(-Float::INFINITY, r.begin)
+    assert_equal today, r.end
+    assert_equal false, r.cover?(today+1)
+    assert_equal true, r.cover?(today-1)
+  end
 
   def test__const
     assert_nil(Date::MONTHNAMES[0])