[YS-531] feature: 공고 매칭 이메일 전송 시 UTM 파라미터 추가

application/src/main/kotlin/com/dobby/usecase/member/email/SendMatchingEmailUseCase.kt

@@ -11,6 +11,7 @@ import com.dobby.model.experiment.ExperimentPost
 import com.dobby.usecase.UseCase
 import com.dobby.util.EmailUtils
 import com.dobby.util.RetryUtils
+import com.dobby.util.UtmLinkUtils
 import java.time.LocalDate
 import java.time.LocalDateTime
 import java.time.format.DateTimeFormatter
@@ -70,13 +71,15 @@ class SendMatchingEmailUseCase(
         return groupedPosts.flatMap { (place, posts) ->
             val sortedPosts = posts.sortedBy { it.createdAt }
             sortedPosts.mapIndexed { index, post ->
-                val postUrl = urlGeneratorGateway.getExperimentPostUrl(post.id)
+                val baseUrl = urlGeneratorGateway.getExperimentPostUrl(post.id)
+                val postUrlWithUtm = UtmLinkUtils.add(baseUrl)
+
                 mapOf(
                     "title" to post.title,
                     "place" to if (index == 0) place else "",
                     "uploadDate" to LocalDate.now().toString(),
                     "reward" to post.reward,
-                    "postUrl" to postUrl
+                    "postUrl" to postUrlWithUtm
                 )
             }
         }

application/src/main/kotlin/com/dobby/util/UtmLinkUtils.kt

@@ -0,0 +1,11 @@
+package com.dobby.util
+
+object UtmLinkUtils {
+    private const val EMAIL_UTM = "utm_source=email&utm_medium=daily"
+
+    fun add(url: String, utm: String = EMAIL_UTM): String {
+        if (url.contains("utm_source=") || url.contains("utm_medium=")) return url
+        val sep = if (url.contains("?")) "&" else "?"
+        return url + sep + utm
+    }
+}

application/src/test/kotlin/com/dobby/util/UtmLinkUtilsTest.kt

@@ -0,0 +1,33 @@
+package com.dobby.util
+
+import io.kotest.core.spec.style.BehaviorSpec
+import io.kotest.matchers.shouldBe
+
+class UtmLinkUtilsTest : BehaviorSpec({
+
+    given("메일 트래킹 정책(utm_source=email&utm_medium=daily)") {
+        `when`("원본 쿼리스트링이 없는 URL이면") {
+            val url = "https://gradmeet.co.kr/post/123"
+            then("UTM이 ?로 시작하여 붙는다") {
+                UtmLinkUtils.add(url) shouldBe
+                    "https://gradmeet.co.kr/post/123?utm_source=email&utm_medium=daily"
+            }
+        }
+
+        `when`("이미 쿼리스트링이 있는 URL이면") {
+            val url = "https://gradmeet.co.kr/post/123?param=test"
+            then("UTM이 &로 붙는다") {
+                UtmLinkUtils.add(url) shouldBe
+                    "https://gradmeet.co.kr/post/123?param=test&utm_source=email&utm_medium=daily"
+            }
+        }
+
+        `when`("이미 동일한 UTM이 붙어 있는 URL이면") {
+            val url = "https://gradmeet.co.kr/321?utm_source=email&utm_medium=daily"
+            then("중복 추가하지 않는다") {
+                UtmLinkUtils.add(url) shouldBe
+                    "https://gradmeet.co.kr/321?utm_source=email&utm_medium=daily"
+            }
+        }
+    }
+})