Here's the revised patch and semi-integrated test

lib/active_record/connection_adapters/sqlserver/quoting.rb

@@ -67,7 +67,15 @@ def quoted_false
 
         def quoted_datetime(value)
           if value.acts_like?(:time)
-            value.is_a?(Date) ? quoted_value_acts_like_time_filter(value).to_time.xmlschema.to(18) : quoted_value_acts_like_time_filter(value).iso8601(3).to(22)
+            time_zone_qualified_value = quoted_value_acts_like_time_filter(value)
+            if value.is_a?(Date)
+              time_zone_qualified_value.to_time.xmlschema.to(18)
+            else
+              if value.is_a?(ActiveSupport::TimeWithZone)
+                time_zone_qualified_value = time_zone_qualified_value.to_time
+              end
+              time_zone_qualified_value.iso8601(3).to(22)
+            end
           else
             quoted_date(value)
           end

test/cases/adapter_test_sqlserver.rb

@@ -337,7 +337,7 @@ def setup
   end
 
   context 'For Quoting' do
-    
+
     should 'return 1 for #quoted_true' do
       assert_equal '1', @connection.quoted_true
     end
@@ -366,7 +366,268 @@ def setup
       assert_equal '[foo].[bar]', @connection.quote_column_name('foo.bar')
       assert_equal '[foo].[bar].[baz]', @connection.quote_column_name('foo.bar.baz')
     end
-
+
+    context "#quote" do
+
+      context "string and multibyte values" do
+
+        context "on an activerecord :integer column" do
+
+          setup do
+            @column = stub("column", :type => :integer)
+          end
+
+          should "return null for empty string" do
+            assert_nil @connection.quote('', @column)
+          end
+
+        end
+
+        context "on an activerecord :binary column" do
+
+          setup do
+            @column = stub("column", :type => :binary)
+          end
+
+          should "ask the column class to convert the value" do
+            value = "value"
+            result = stub("result")
+            @column.class.stubs(:string_to_binary).with(value).returns(result)
+            assert_equal result, @connection.quote(value, @column)
+          end
+
+        end
+
+        context "on an activerecord :string column or with any value that is_utf8?" do
+
+          should "surround it when N'...'" do
+            assert_equal "N'foo'", @connection.quote("foo")
+          end
+
+          should "escape all single quotes by repeating them" do
+            assert_equal "N'''quotation''s'''", @connection.quote("'quotation's'")
+          end
+
+        end
+
+        context "with a value that's not is_utf8?" do
+
+          setup do
+            @value = "value"
+            @value.stubs(:is_utf8? => false)
+          end
+
+          should_eventually "call super"
+
+        end
+
+      end
+
+      context "date and time values" do
+
+        setup do
+          @value = Date.today
+        end
+
+        context "on a sql datetime column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'datetime')
+          end
+
+          should "call quoted_datetime and surrounds its result with single quotes" do
+            @connection.stubs(:quoted_datetime).with(@value).returns("2000-01-01")
+            assert_equal "'2000-01-01'", @connection.quote(@value, @column)
+          end
+
+        end
+
+        context "on a sql datetimeoffset column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'datetimeoffset')
+          end
+
+          should "call quoted_full_iso8601 and surrounds its result with single quotes" do
+            @connection.stubs(:quoted_full_iso8601).with(@value).returns("2000-01-01")
+            assert_equal "'2000-01-01'", @connection.quote(@value, @column)
+          end
+
+        end
+
+        context "on a sql time column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'time')
+          end
+
+          should "call quoted_full_iso8601 and surrounds its result with single quotes" do
+            @connection.stubs(:quoted_full_iso8601).with(@value).returns("2000-01-01")
+            assert_equal "'2000-01-01'", @connection.quote(@value, @column)
+          end
+
+        end
+
+        context "with another sql column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'foo')
+          end
+
+          should_eventually "call super"
+
+        end
+
+        context "with no column" do
+
+          should_eventually "call super"
+
+        end
+
+      end
+
+      context "nil values" do
+
+        context "on a sql timestamp column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'timestamp')
+          end
+
+          should "return DEFAULT" do
+            assert_equal "DEFAULT", @connection.quote(nil, @column)
+          end
+
+        end
+
+        context "with another sql column" do
+
+          setup do
+            @column = stub("column", :sql_type => 'foo')
+          end
+
+          should_eventually "call super"
+
+        end
+
+      end
+
+      context "other values" do
+
+        setup do
+          @value = stub("value")
+        end
+
+        should_eventually "call super"
+
+      end
+
+    end
+
+    context "#quoted_datetime" do
+
+      context "with a Date" do
+
+        setup do
+          @value = Date.parse('2001-02-03T04:05:06-0700')
+          assert @value.is_a?(Date)
+        end
+
+        should "return a dd-mm-yyyy date string" do
+          assert_equal '02-03-2001', @connection.quoted_datetime(@value)
+        end
+
+      end
+
+      context "when the ActiveRecord default timezone is UTC" do
+
+        setup do
+          @old_activerecord_timezone = ActiveRecord::Base.default_timezone
+          ActiveRecord::Base.default_timezone = :utc
+        end
+
+        teardown do
+          ActiveRecord::Base.default_timezone = @old_activerecord_timezone
+          @old_activerecord_timezone = nil
+        end
+
+        context "with a Time" do
+
+          setup do
+            @value = Time.parse('2001-02-03T04:05:06-0700')
+            assert @value.is_a?(Time)
+          end
+
+          should "return an ISO 8601 datetime string" do
+            assert_equal '2001-02-03T11:05:06.000', @connection.quoted_datetime(@value)
+          end
+
+        end
+
+        context "with a DateTime" do
+
+          setup do
+            @value = DateTime.parse('2001-02-03T04:05:06-0700')
+            assert @value.is_a?(DateTime)
+          end
+
+          should "return an ISO 8601 datetime string" do
+            assert_equal '2001-02-03T11:05:06', @connection.quoted_datetime(@value)
+          end
+
+        end
+
+        context "with an ActiveSupport::TimeWithZone" do
+
+          setup do
+            require 'tzinfo'
+            @old_zone = Time.zone
+            Time.zone = 'Eastern Time (US & Canada)'
+          end
+
+          teardown do
+            Time.zone = @old_zone
+            @old_zone = nil
+          end
+
+          context "wrapping a datetime" do
+
+            setup do
+              @value = DateTime.parse('2001-02-03T04:05:06-0700').in_time_zone
+              assert @value.is_a?(ActiveSupport::TimeWithZone)
+            end
+
+            should "return an ISO 8601 datetime string with milliseconds" do
+              assert_equal '2001-02-03T11:05:06.000', @connection.quoted_datetime(@value)
+            end
+
+          end
+
+          context "wrapping a time" do
+
+            setup do
+              @value = Time.parse('2001-02-03T04:05:06-0700').in_time_zone
+              assert @value.is_a?(ActiveSupport::TimeWithZone)
+            end
+
+            should "return an ISO 8601 datetime string with milliseconds" do
+              assert_equal '2001-02-03T11:05:06.000', @connection.quoted_datetime(@value)
+            end
+
+          end
+
+        end
+
+        context "with a String" do
+
+          should_eventually "call quoted_date on super"
+
+        end
+
+      end
+
+    end
+
   end
 
   context 'When disabling referential integrity' do