Bidding the opponent’s suit to reach 4Hearts for NS

Question

E bids 1Spade, S O/c 2 Hearts, W bids 2 Spades and N bids the opponent’s suit 3 Spades. Partner now (somewhat reluctantly) bids 4 Heats and makes the contract. Thank you Bernard.! We were the only ones in 4 Hearts making and got 100%.