Legislation to allow gay and lesbian couples to marry in Rhode Island will soon head to its first political test. The House Judiciary Committee has scheduled a vote on the measure Tuesday. If the panel passes the measure, as expected, it will head to the full House for a vote, possibly next week. House Speaker Gordon Fox has said he wants the House to vote on the legislation by month’s end. Advocates for gay marriage like their chances in the House, but concede that the Senate is a tougher challenge. Rhode Island is the only state in New England that does not allow same-sex marriage.