extract github pull request merge message

src/main/java/cholog/discord/message/GithubPullRequestMergeMessage.java

@@ -0,0 +1,23 @@
+package cholog.discord.message;
+
+import cholog.github.PullRequestUrl;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class GithubPullRequestMergeMessage {
+
+    private final String rawMessage;
+
+    public GithubPullRequestMergeMessage(final String rawMessage) {
+        this.rawMessage = rawMessage;
+    }
+
+    public List<PullRequestUrl> extractUrls() {
+        return Arrays.stream(rawMessage.split("\\s+"))
+                .map(String::trim)
+                .filter(it -> it.startsWith("http"))
+                .map(PullRequestUrl::new)
+                .toList();
+    }
+}

src/main/java/cholog/discord/message/GithubPullRequestMergeSubscription.java

@@ -44,6 +44,10 @@ public void onEvent(final MessageReceivedEvent event) {
                 .map(String::trim)
                 .filter(it -> it.startsWith("http"))
                 .toList();
+        if (urls.isEmpty()) {
+            log.debug("No URLs found in message [message={}]", message);
+            return;
+        }
 
         final var fails = new HashMap<String, String>();
         for (final String url : urls) {

src/test/java/cholog/discord/message/GithubPullRequestMergeMessageTest.java

@@ -0,0 +1,49 @@
+package cholog.discord.message;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertAll;
+
+class GithubPullRequestMergeMessageTest {
+
+    @Test
+    void extractUrls_lastComment() {
+        final var message = new GithubPullRequestMergeMessage("""
+                https://github.com/next-step/java-lotto-clean-playground/pull/35
+                https://github.com/next-step/java-lotto-clean-playground/pull/37
+                https://github.com/next-step/java-lotto-clean-playground/pull/39
+                https://github.com/next-step/java-lotto-clean-playground/pull/40
+                                
+                머지 요청드립니다!""");
+
+        final var extractUrls = message.extractUrls();
+
+        assertAll(
+                () -> assertThat(extractUrls).hasSize(4),
+                () -> assertThat(extractUrls.getFirst().pullNumber()).isEqualTo(35),
+                () -> assertThat(extractUrls.getLast().pullNumber()).isEqualTo(40)
+        );
+    }
+
+    @Test
+    void extractUrls_firstComment() {
+        final var message = new GithubPullRequestMergeMessage("""
+                머지요청드립니다 (자동차) :chologe:\s
+                https://github.com/next-step/java-racingcar-simple-playground/pull/30
+                https://github.com/next-step/java-racingcar-simple-playground/pull/44
+                https://github.com/next-step/java-racingcar-simple-playground/pull/45
+                https://github.com/next-step/java-racingcar-simple-playground/pull/46
+                https://github.com/next-step/java-racingcar-simple-playground/pull/48
+                https://github.com/next-step/java-racingcar-simple-playground/pull/49
+                """);
+
+        final var extractUrls = message.extractUrls();
+
+        assertAll(
+                () -> assertThat(extractUrls).hasSize(6),
+                () -> assertThat(extractUrls.getFirst().pullNumber()).isEqualTo(30),
+                () -> assertThat(extractUrls.getLast().pullNumber()).isEqualTo(49)
+        );
+    }
+}