Added an Iso8601TimeRange class to manage ranges in ISO8601 format.

lib/iso8601_time_range.rb

@@ -0,0 +1,18 @@
+class Iso8601TimeRange
+  def initialize(time_range)
+    raise ArgumentError.new("A TimeRange argument is needed") unless time_range.is_a?(TimeRange)
+    @time_range = time_range
+  end
+
+  def start
+    @time_range.start.utc.iso8601
+  end
+
+  def finish
+    @time_range.finish.utc.iso8601
+  end
+
+  def to_s
+    "#{start}~#{finish}"
+  end
+end

spec/lib/iso8601_time_range_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe Iso8601TimeRange do
+  context "when not initialized with a TimeRange" do
+    it "should raise error" do
+      expect{
+        Iso8601TimeRange.new([1, 2])
+      }.to raise_error ArgumentError
+    end
+  end
+
+  context "when initialized with a TimeRange" do
+    let(:time_range) { TimeRange.today }
+    subject { Iso8601TimeRange.new(time_range) }
+
+    it { subject.start.should == time_range.start.utc.iso8601 }
+    it { subject.finish.should == time_range.finish.utc.iso8601 }
+  end
+end