feat: 쿠폰 사용 - 쿠폰 사용 완료 안내 문구 적용

src/main/kotlin/kr/co/vividnext/sodalive/can/charge/ChargeService.kt

@@ -67,7 +67,7 @@ class ChargeService(
 ) {
 
     @Transactional
-    fun chargeByCoupon(couponNumber: String, member: Member) {
+    fun chargeByCoupon(couponNumber: String, member: Member): String {
         val canCouponNumber = couponNumberRepository.findByCouponNumber(couponNumber = couponNumber)
             ?: throw SodaException("잘못된 쿠폰번호입니다.\n고객센터로 문의해 주시기 바랍니다.")
 
@@ -93,6 +93,7 @@ class ChargeService(
                 chargeRepository.save(couponCharge)
 
                 member.charge(0, coupon.can, "pg")
+                return "쿠폰 사용이 완료되었습니다. ${coupon.can}캔이 지급되었습니다."
             }
 
             CouponType.POINT -> {
@@ -119,6 +120,8 @@ class ChargeService(
                         expiresAt = LocalDateTime.now().plusDays(3)
                     )
                 )
+
+                return "쿠폰 사용이 완료되었습니다. ${coupon.can}포인트가 지급되었습니다."
             }
         }
     }

src/main/kotlin/kr/co/vividnext/sodalive/can/coupon/CanCouponController.kt

@@ -109,11 +109,11 @@ class CanCouponController(private val service: CanCouponService) {
     ) = run {
         if (member == null) throw SodaException("로그인 정보를 확인해주세요.")
 
-        ApiResponse.ok(
-            service.useCanCoupon(
-                couponNumber = request.couponNumber,
-                memberId = member.id!!
-            )
+        val completeMessage = service.useCanCoupon(
+            couponNumber = request.couponNumber,
+            memberId = member.id!!
         )
+
+        ApiResponse.ok(Unit, completeMessage)
     }
 }

src/main/kotlin/kr/co/vividnext/sodalive/can/coupon/CanCouponService.kt

@@ -121,7 +121,7 @@ class CanCouponService(
         }
     }
 
-    fun useCanCoupon(couponNumber: String, memberId: Long) {
+    fun useCanCoupon(couponNumber: String, memberId: Long): String {
         val member = memberRepository.findByIdOrNull(id = memberId)
             ?: throw SodaException("로그인 정보를 확인해주세요.")
 
@@ -129,7 +129,7 @@ class CanCouponService(
 
         issueService.validateAvailableUseCoupon(couponNumber, memberId)
 
-        chargeService.chargeByCoupon(couponNumber, member)
+        return chargeService.chargeByCoupon(couponNumber, member)
     }
 
     private fun insertHyphens(input: String): String {