Added DateTypecaster, for #5

active_attr.gemspec

@@ -25,4 +25,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency "factory_girl", "~> 2.2"
   s.add_development_dependency "rake",         "~> 0.9.0"
   s.add_development_dependency "rspec",        "~> 2.6"
+  s.add_development_dependency "tzinfo",       "~> 0.3.29"
 end

lib/active_attr/typecasting.rb

@@ -1,3 +1,4 @@
+require "active_attr/typecasting/date_typecaster"
 require "active_attr/typecasting/float_typecaster"
 require "active_attr/typecasting/integer_typecaster"
 require "active_attr/typecasting/string_typecaster"
@@ -12,9 +13,10 @@ module Typecasting
 
     # @private
     TYPECASTERS = {
-      Float    => FloatTypecaster,
-      Integer  => IntegerTypecaster,
-      String   => StringTypecaster,
+      Date    => DateTypecaster,
+      Float   => FloatTypecaster,
+      Integer => IntegerTypecaster,
+      String  => StringTypecaster,
     }
 
     # Typecasts a value using a Class

lib/active_attr/typecasting/date_typecaster.rb

@@ -0,0 +1,15 @@
+require "date"
+require "active_support/core_ext/date/conversions"
+require "active_support/core_ext/date_time/conversions"
+require "active_support/core_ext/string/conversions"
+require "active_support/core_ext/time/publicize_conversion_methods"
+
+module ActiveAttr
+  module Typecasting
+    class DateTypecaster
+      def call(value)
+        value.to_date if value.respond_to? :to_date
+      end
+    end
+  end
+end

spec/unit/active_attr/typecasting/date_typecaster_spec.rb

@@ -0,0 +1,51 @@
+require "spec_helper"
+require "active_attr/typecasting/date_typecaster"
+
+module ActiveAttr
+  module Typecasting
+    describe DateTypecaster do
+      describe "#call" do
+        it "returns the original date for a Date" do
+          value = Date.today
+          subject.call(value).should equal value
+        end
+
+        it "casts a UTC Time to a Date representing the date portion" do
+          subject.call(Time.utc(2012, 1, 1, 0, 0, 0)).should == Date.new(2012, 1, 1)
+        end
+
+        it "casts a local Time to a Date representing the date portion" do
+          subject.call(Time.local(2012, 1, 1, 0, 0, 0)).should == Date.new(2012, 1, 1)
+        end
+
+        it "casts a UTC DateTime to a Date representing the date portion" do
+          subject.call(DateTime.new(2012, 1, 1, 0, 0, 0)).should == Date.new(2012, 1, 1)
+        end
+
+        it "casts an offset DateTime to a Date representing the date portion" do
+          subject.call(DateTime.new(2012, 1, 1, 0, 0, 0, "-12:00")).should == Date.new(2012, 1, 1)
+        end
+
+        it "casts an ISO8601 date String to a Date" do
+          subject.call("2012-01-01").should == Date.new(2012, 1, 1)
+        end
+
+        it "casts an RFC2616 date and GMT time String to a Date representing the date portion" do
+          subject.call("Sat, 03 Feb 2001 00:00:00 GMT").should == Date.new(2001, 2, 3)
+        end
+
+        it "casts an RFC3339 date and offset time String to a Date representing the date portion" do
+          subject.call("2001-02-03T04:05:06+07:00").should == Date.new(2001, 2, 3)
+        end
+
+        it "casts a UTC ActiveSupport::TimeWithZone to a Date representing the date portion" do
+          subject.call(Time.utc(2012, 1, 1, 0, 0, 0).in_time_zone("UTC")).should == Date.new(2012, 1, 1)
+        end
+
+        it "casts an Alaska ActiveSupport::TimeWithZone to a Date representing the date portion" do
+          subject.call(Time.utc(2012, 1, 1, 0, 0, 0).in_time_zone("Alaska")).should == Date.new(2011, 12, 31)
+        end
+      end
+    end
+  end
+end

spec/unit/active_attr/typecasting_spec.rb

@@ -87,6 +87,11 @@ module ActiveAttr
         Typecasting::IntegerTypecaster.any_instance.should_receive(:call).with(value)
         model.typecast_value(Integer, value)
       end
+
+      it "calls DateTypecaster when typecasting to Date" do
+        Typecasting::DateTypecaster.any_instance.should_receive(:call).with(value)
+        model.typecast_value(Date, value)
+      end
     end
   end
 end