Add coverage for empty lists.

Author: ioquatix

test/async/list.rb

@@ -131,6 +131,10 @@ def initialize(value)
 	end
 
 	with '#first' do
+		it "returns nil for an empty list" do
+			expect(list.first).to be_nil
+		end
+		
 		it "can return the first item" do
 			item = Item.new(1)
 
@@ -143,6 +147,10 @@ def initialize(value)
 	end
 
 	with '#last' do
+		it "returns nil for an empty list" do
+			expect(list.last).to be_nil
+		end
+		
 		it "can return the last item" do
 			item = Item.new(1)