fix rule for expression expression; fix tests

lib/text_to_sql_query.rb

@@ -15,11 +15,10 @@ class TextToSqlQuery
     end
   end
 
-  def where_clause(model)
+  def where_clause
     @parser = Query.new
     @parsed_tree = @parser.parse(@text)
-    generated_sql = generate_sql @parsed_tree
-    model.where generated_sql
+    generate_sql @parsed_tree
   end
 
   private