Update with semantics of MSC4102

tests/csapi/thread_notifications_test.go

@@ -303,8 +303,8 @@ func TestThreadedReceipts(t *testing.T) {
 }
 
 // Regression test for https://github.com/matrix-org/matrix-spec/issues/1727
-// Servers need to send 2x EDUs to represent these 2 receipts, but do they?
-func TestThreadReceiptsInSync(t *testing.T) {
+// Servers should always prefer the unthreaded receipt when there is a clash of receipts
+func TestThreadReceiptsInSyncMSC4102(t *testing.T) {
 	runtime.SkipIf(t, runtime.Dendrite) // not supported
 	deployment := complement.Deploy(t, 1)
 	defer deployment.Destroy(t)
@@ -330,38 +330,15 @@ func TestThreadReceiptsInSync(t *testing.T) {
 			},
 		},
 	})
-	// now send an unthreaded RR for event B and a threaded RR for event B and ensure we see both receipts
+	// now send an unthreaded RR for event B and a threaded RR for event B and ensure we see the unthreaded RR
 	// down /sync. Non-compliant servers will typically send the last one only.
 	alice.MustDo(t, "POST", []string{"_matrix", "client", "v3", "rooms", roomID, "receipt", "m.read", eventB}, client.WithJSONBody(t, struct{}{}))
 	alice.MustDo(t, "POST", []string{"_matrix", "client", "v3", "rooms", roomID, "receipt", "m.read", eventB}, client.WithJSONBody(t, map[string]interface{}{"thread_id": eventA}))
 
-	seenThreaded := false
-	seenUnthreaded := false
-
 	alice.MustSyncUntil(
 		t,
 		client.SyncReq{},
-		// we need to allow multiple /sync responses to gradually show us both receipts, hence the weird shape here.
-		func(clientUserID string, topLevelSyncJSON gjson.Result) error {
-			var lastErr error
-			if err := syncHasUnthreadedReadReceipt(roomID, alice.UserID, eventB)(clientUserID, topLevelSyncJSON); err == nil {
-				seenUnthreaded = true
-				t.Logf("seen unthreaded read receipt")
-			} else {
-				lastErr = err
-			}
-			if err := syncHasThreadedReadReceipt(roomID, alice.UserID, eventB, eventA)(clientUserID, topLevelSyncJSON); err == nil {
-				seenThreaded = true
-				t.Logf("seen threaded read receipt")
-			} else {
-				lastErr = err
-			}
-			if seenThreaded && seenUnthreaded {
-				t.Logf("seen both read receipts, returning")
-				return nil
-			}
-			return lastErr
-		},
+		syncHasUnthreadedReadReceipt(roomID, alice.UserID, eventB),
 	)
 
 }