Add test cases for array and hash for #to_param

to_query_test.rb is testing hash actually, but it is missing 2 cases. Okay I will move these to to_query_test.rb.
But Array#to_param doesn't depend on to_query, but when it has hash as an element in it, we require to_query. So should we test Array#to_param in to_query_test.rb?