Fix kotlin weekly issue number parsing.

Author: ychescale9

src/main/kotlin/io/github/reactivecircus/kstreamlined/backend/datafetcher/mapper/KotlinWeeklyEntryMapper.kt

@@ -6,16 +6,17 @@ import java.time.ZonedDateTime
 import java.time.format.DateTimeFormatter
 
 fun KotlinWeeklyItem.toKotlinWeeklyEntry(): KotlinWeekly {
+    val issueNumber = linkIssueNumberRegex.find(link)?.groupValues?.get(1)?.toInt()
+        ?: error("Issue number not found in link: $link")
     return KotlinWeekly(
         id = guid,
         title = title,
         publishTime = ZonedDateTime
             .parse(pubDate, DateTimeFormatter.RFC_1123_DATE_TIME)
             .toInstant(),
         contentUrl = link,
-        issueNumber = issueNumberRegex.find(title)?.groupValues?.get(1)?.toInt()
-            ?: error("Issue number not found in title: $title")
+        issueNumber = issueNumber,
     )
 }
 
-private val issueNumberRegex = Regex("#(\\d+)")
+private val linkIssueNumberRegex = Regex("kotlin-weekly-(\\d+)", RegexOption.IGNORE_CASE)

src/test/kotlin/io/github/reactivecircus/kstreamlined/backend/datafetcher/mapper/KotlinWeeklyEntryMapperTest.kt

@@ -28,12 +28,12 @@ class KotlinWeeklyEntryMapperTest {
     }
 
     @Test
-    fun `toKotlinWeeklyEntry() throws exception when issueNumber not found in title`() {
+    fun `toKotlinWeeklyEntry() throws exception when issueNumber not found in link`() {
         assertFailsWith<IllegalStateException> {
             KotlinWeeklyItem(
                 title = "Kotlin Weekly X",
-                link = "https://mailchi.mp/kotlinweekly/kotlin-weekly-381",
-                guid = "https://mailchi.mp/kotlinweekly/kotlin-weekly-381",
+                link = "https://mailchi.mp/kotlinweekly/random-newsletter",
+                guid = "https://mailchi.mp/kotlinweekly/random-newsletter",
                 pubDate = "Sun, 19 Nov 2023 09:13:00 +0000",
             ).toKotlinWeeklyEntry()
         }