fix: invalidate group settings cache on membership changes

server/store/group_message_runtime_test.go

@@ -13,6 +13,7 @@ type testGroupMessageRuntime struct {
 	seqs            map[string]int64
 	shortStates     map[string]bool
 	deletedPrefixes []string
+	deletedObjects  []string
 }
 
 func newTestGroupMessageRuntime() *testGroupMessageRuntime {
@@ -152,7 +153,8 @@ func (r *testGroupMessageRuntime) GetCachedObject(types.TenantID, string, string
 	return false, nil
 }
 
-func (r *testGroupMessageRuntime) DeleteCachedObject(types.TenantID, string, string) error {
+func (r *testGroupMessageRuntime) DeleteCachedObject(_ types.TenantID, namespace, id string) error {
+	r.deletedObjects = append(r.deletedObjects, namespace+":"+id)
 	return nil
 }
 
@@ -311,3 +313,15 @@ func TestInvalidateGroupMemberPagesUsesTopicKeyPrefix(t *testing.T) {
 		t.Fatalf("unexpected deleted prefixes: %#v", runtime.deletedPrefixes)
 	}
 }
+
+func TestInvalidateGroupSettingsUsesTopicCacheKey(t *testing.T) {
+	oldRuntime := groupMsgRuntime
+	runtime := newTestGroupMessageRuntime()
+	groupMsgRuntime = runtime
+	t.Cleanup(func() { groupMsgRuntime = oldRuntime })
+
+	invalidateGroupSettings(7, " grpAlpha ")
+	if len(runtime.deletedObjects) != 1 || runtime.deletedObjects[0] != "group_settings:grpAlpha" {
+		t.Fatalf("unexpected deleted objects: %#v", runtime.deletedObjects)
+	}
+}