Expand sql engine CRUD specs

spec/arel/engines/sql/unit/engine_spec.rb

@@ -3,32 +3,41 @@
 module Arel
   describe Sql::Engine do
     before do
-      @relation = Table.new(:users)
+      @users = Table.new(:users)
+      @users.delete
     end
 
     describe "CRUD" do
       describe "#create" do
         it "inserts into the relation" do
-          @relation.insert @relation[:name] => "Bryan"
+          @users.insert @users[:name] => "Bryan"
+          @users.first[@users[:name]].should == "Bryan"
         end
       end
 
       describe "#read" do
         it "reads from the relation" do
-          @relation.each do |row|
+          @users.insert @users[:name] => "Bryan"
+
+          @users.each do |row|
+            row[@users[:name]].should == "Bryan"
           end
         end
       end
 
       describe "#update" do
         it "updates the relation" do
-          @relation.update @relation[:name] => "Bryan"
+          @users.insert @users[:name] => "Nick"
+          @users.update @users[:name] => "Bryan"
+          @users.first[@users[:name]].should == "Bryan"
         end
       end
 
       describe "#delete" do
         it "deletes from the relation" do
-          @relation.delete
+          @users.insert @users[:name] => "Bryan"
+          @users.delete
+          @users.first.should == nil
         end
       end
     end