public List<TradeHistoryResponse> findTradeHistories(final Long memberId, final boolean isSeller) {
        if (isSeller) {
            return findHistories(memberId, tradeHistory.sellerId::eq);
        }

        return findHistories(memberId, tradeHistory.buyerId::eq);
    }
@Test
    void 구매자의_구매_내역을_조회한다() {
        // when
        List<TradeHistoryResponse> result = tradeHistoryQueryRepository.findTradeHistories(buyer.getId(), false);

        // then
        assertSoftly(softly -> {
            softly.assertThat(result).hasSize(1);
            softly.assertThat(result.get(0).buyerName()).isEqualTo(buyer.getNickname());
            softly.assertThat(result.get(0).sellerName()).isEqualTo(seller.getNickname());
            softly.assertThat(result.get(0).productTitle()).isEqualTo(product.getDescription().getTitle());
        });
    }