test(issues): pin plural @JsonTypeName for discussion events

Add DiscussionEventChannelJsonTest asserting the on-the-wire @type for the four discussion events stays the canonical plural webprotege.events.discussions.* form, so the drift in #54 fails the build instead of silently dropping events.

Refs #54

Author: johardi

src/test/java/edu/stanford/protege/webprotege/issues/DiscussionEventChannelJsonTest.java

@@ -0,0 +1,116 @@
+package edu.stanford.protege.webprotege.issues;
+
+import com.google.common.collect.ImmutableList;
+import edu.stanford.protege.webprotege.common.EventId;
+import edu.stanford.protege.webprotege.common.ProjectId;
+import edu.stanford.protege.webprotege.common.UserId;
+import org.junit.jupiter.api.Test;
+import org.semanticweb.owlapi.model.OWLClass;
+import org.semanticweb.owlapi.vocab.OWLRDFVocabulary;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.json.JsonTest;
+import org.springframework.boot.test.json.JacksonTester;
+import org.springframework.boot.test.json.JsonContent;
+import uk.ac.manchester.cs.owl.owlapi.OWLClassImpl;
+
+import java.util.Optional;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Contract-guard tests that pin the on-the-wire {@code @JsonTypeName} discriminator for
+ * every event in the discussion namespace.
+ *
+ * <p>These events are routed across the JSON-RPC envelope by their {@code @JsonTypeName}
+ * value. If a discriminator drifts (for example the canonical plural {@code discussions}
+ * silently reverts to the singular {@code discussion}), the consumer treats the message as
+ * an unknown type and drops it — no exception is thrown on either side. See
+ * protegeproject/webprotege-backend-api#54.
+ *
+ * <p>The expected values below are hard-coded on purpose: asserting against each class's
+ * own {@code CHANNEL} constant would let a constant rename slip through undetected. The
+ * whole point of this test is to fail the build if any of these strings ever change.
+ */
+@JsonTest
+class DiscussionEventChannelJsonTest {
+
+    private static final String PROJECT_ID = "00000000-1111-2222-3333-444444444444";
+
+    private static final String COMMENT_POSTED = "webprotege.events.discussions.CommentPosted";
+
+    private static final String COMMENT_UPDATED = "webprotege.events.discussions.CommentUpdated";
+
+    private static final String STATUS_CHANGED = "webprotege.events.discussions.DiscussionThreadStatusChanged";
+
+    private static final String THREAD_CREATED = "webprotege.events.discussions.DiscussionThreadCreated";
+
+    @Autowired
+    private JacksonTester<CommentPostedEvent> commentPostedTester;
+
+    @Autowired
+    private JacksonTester<CommentUpdatedEvent> commentUpdatedTester;
+
+    @Autowired
+    private JacksonTester<DiscussionThreadStatusChangedEvent> statusChangedTester;
+
+    @Autowired
+    private JacksonTester<DiscussionThreadCreatedEvent> threadCreatedTester;
+
+    private static EventId eventId() {
+        return new EventId("event-id");
+    }
+
+    private static ProjectId projectId() {
+        return new ProjectId(PROJECT_ID);
+    }
+
+    private static ThreadId threadId() {
+        return ThreadId.valueOf("thread-id");
+    }
+
+    private static Comment comment() {
+        return new Comment(CommentId.valueOf("comment-id"),
+                           UserId.valueOf("the-user"),
+                           0L,
+                           Optional.empty(),
+                           "body",
+                           "renderedBody");
+    }
+
+    @Test
+    void commentPostedEventSerializesWithPluralDiscriminator() throws Exception {
+        var event = new CommentPostedEvent(eventId(), projectId(), threadId(), comment(),
+                                           Optional.empty(), 0, 0);
+        JsonContent<CommentPostedEvent> json = commentPostedTester.write(event);
+        assertThat(json).extractingJsonPathStringValue("$.['@type']").isEqualTo(COMMENT_POSTED);
+        assertThat(CommentPostedEvent.CHANNEL).isEqualTo(COMMENT_POSTED);
+    }
+
+    @Test
+    void commentUpdatedEventSerializesWithPluralDiscriminator() throws Exception {
+        var event = new CommentUpdatedEvent(eventId(), projectId(), threadId(), comment());
+        JsonContent<CommentUpdatedEvent> json = commentUpdatedTester.write(event);
+        assertThat(json).extractingJsonPathStringValue("$.['@type']").isEqualTo(COMMENT_UPDATED);
+        assertThat(CommentUpdatedEvent.CHANNEL).isEqualTo(COMMENT_UPDATED);
+    }
+
+    @Test
+    void discussionThreadStatusChangedEventSerializesWithPluralDiscriminator() throws Exception {
+        var event = new DiscussionThreadStatusChangedEvent(eventId(), projectId(), threadId(),
+                                                           Optional.empty(), 0, Status.OPEN);
+        JsonContent<DiscussionThreadStatusChangedEvent> json = statusChangedTester.write(event);
+        assertThat(json).extractingJsonPathStringValue("$.['@type']").isEqualTo(STATUS_CHANGED);
+        assertThat(DiscussionThreadStatusChangedEvent.CHANNEL).isEqualTo(STATUS_CHANGED);
+    }
+
+    @Test
+    void discussionThreadCreatedEventSerializesWithPluralDiscriminator() throws Exception {
+        OWLClass entity = new OWLClassImpl(OWLRDFVocabulary.OWL_THING.getIRI());
+        var thread = new EntityDiscussionThread(threadId(), projectId(), entity, Status.OPEN,
+                                                ImmutableList.of());
+        var event = new DiscussionThreadCreatedEvent(eventId(), projectId(), thread);
+        JsonContent<DiscussionThreadCreatedEvent> json = threadCreatedTester.write(event);
+        assertThat(json).extractingJsonPathStringValue("$.['@type']").isEqualTo(THREAD_CREATED);
+        assertThat(DiscussionThreadCreatedEvent.CHANNEL).isEqualTo(THREAD_CREATED);
+    }
+}