require'spec_helper'describeGitlab::SQL::Uniondodescribe'#to_sql'doit'returns a String joining relations together using a UNION'dorel1=User.where(email: 'alice@example.com')rel2=User.where(email: 'bob@example.com')union=described_class.new([rel1,rel2])sql1=rel1.reorder(nil).to_sqlsql2=rel2.reorder(nil).to_sql