Revert "Remove test that is no longer needed"

This reverts commit 9a45babff6.

roomserver/roomserver_test.go

@@ -1,6 +1,7 @@
 package roomserver
 
 import (
+	"bytes"
 	"context"
 	"crypto/ed25519"
 	"encoding/json"
@@ -236,3 +237,163 @@ func TestOutputRedactedEvent(t *testing.T) {
 		}
 	}
 }
+
+// This tests that rewriting state via KindRewrite works correctly.
+// This creates a small room with a create/join/name state, then replays it
+// with a new room name. We expect the output events to contain the original events,
+// followed by a single OutputNewRoomEvent with RewritesState set to true with the
+// rewritten state events (with the 2nd room name).
+func TestOutputRewritesState(t *testing.T) {
+	roomID := "!foo:" + string(testOrigin)
+	alice := "@alice:" + string(testOrigin)
+	emptyKey := ""
+	originalEvents := mustCreateEvents(t, gomatrixserverlib.RoomVersionV6, []fledglingEvent{
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"creator":      alice,
+				"room_version": "6",
+			},
+			StateKey: &emptyKey,
+			Type:     gomatrixserverlib.MRoomCreate,
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"membership": "join",
+			},
+			StateKey: &alice,
+			Type:     gomatrixserverlib.MRoomMember,
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"body": "hello world",
+			},
+			StateKey: nil,
+			Type:     "m.room.message",
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"name": "Room Name",
+			},
+			StateKey: &emptyKey,
+			Type:     "m.room.name",
+		},
+	})
+	rewriteEvents := mustCreateEvents(t, gomatrixserverlib.RoomVersionV6, []fledglingEvent{
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"creator": alice,
+			},
+			StateKey: &emptyKey,
+			Type:     gomatrixserverlib.MRoomCreate,
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"membership": "join",
+			},
+			StateKey: &alice,
+			Type:     gomatrixserverlib.MRoomMember,
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"name": "Room Name 2",
+			},
+			StateKey: &emptyKey,
+			Type:     "m.room.name",
+		},
+		{
+			RoomID: roomID,
+			Sender: alice,
+			Content: map[string]interface{}{
+				"body": "hello world 2",
+			},
+			StateKey: nil,
+			Type:     "m.room.message",
+		},
+	})
+	deleteDatabase()
+	rsAPI, producer := mustCreateRoomserverAPI(t)
+	defer deleteDatabase()
+	err := api.SendEvents(context.Background(), rsAPI, originalEvents, testOrigin, nil)
+	if err != nil {
+		t.Fatalf("failed to send original events: %s", err)
+	}
+	// assert we got them produced, this is just a sanity check and isn't the intention of this test
+	if len(producer.producedMessages) != len(originalEvents) {
+		t.Fatalf("SendEvents didn't result in same number of produced output events: got %d want %d", len(producer.producedMessages), len(originalEvents))
+	}
+	producer.producedMessages = nil // we aren't actually interested in these events, just the rewrite ones
+
+	var inputEvents []api.InputRoomEvent
+	// slowly build up the state IDs again, we're basically telling the roomserver what to store as a snapshot
+	var stateIDs []string
+	// skip the last event, we'll use this to tie together the rewrite as the KindNew event
+	for i := 0; i < len(rewriteEvents)-1; i++ {
+		ev := rewriteEvents[i]
+		inputEvents = append(inputEvents, api.InputRoomEvent{
+			Kind:          api.KindOutlier,
+			Event:         ev,
+			AuthEventIDs:  ev.AuthEventIDs(),
+			HasState:      true,
+			StateEventIDs: stateIDs,
+		})
+		if ev.StateKey() != nil {
+			stateIDs = append(stateIDs, ev.EventID())
+		}
+	}
+	lastEv := rewriteEvents[len(rewriteEvents)-1]
+	inputEvents = append(inputEvents, api.InputRoomEvent{
+		Kind:          api.KindNew,
+		Event:         lastEv,
+		AuthEventIDs:  lastEv.AuthEventIDs(),
+		HasState:      true,
+		StateEventIDs: stateIDs,
+	})
+	if err := api.SendInputRoomEvents(context.Background(), rsAPI, inputEvents); err != nil {
+		t.Fatalf("SendInputRoomEvents returned error for rewrite events: %s", err)
+	}
+	// we should just have one output event with the entire state of the room in it
+	if len(producer.producedMessages) != 1 {
+		t.Fatalf("Rewritten events got output, want only 1 got %d", len(producer.producedMessages))
+	}
+	outputEvent := producer.producedMessages[0]
+	if !outputEvent.NewRoomEvent.RewritesState {
+		t.Errorf("RewritesState flag not set on output event")
+	}
+	if !reflect.DeepEqual(stateIDs, outputEvent.NewRoomEvent.AddsStateEventIDs) {
+		t.Errorf("Output event is missing room state event IDs, got %v want %v", outputEvent.NewRoomEvent.AddsStateEventIDs, stateIDs)
+	}
+	if !bytes.Equal(outputEvent.NewRoomEvent.Event.JSON(), lastEv.JSON()) {
+		t.Errorf(
+			"Output event isn't the latest KindNew event:\ngot  %s\nwant %s",
+			string(outputEvent.NewRoomEvent.Event.JSON()),
+			string(lastEv.JSON()),
+		)
+	}
+	if len(outputEvent.NewRoomEvent.AddStateEvents) != len(stateIDs) {
+		t.Errorf("Output event is missing room state events themselves, got %d want %d", len(outputEvent.NewRoomEvent.AddStateEvents), len(stateIDs))
+	}
+	// make sure the state got overwritten, check the room name
+	hasRoomName := false
+	for _, ev := range outputEvent.NewRoomEvent.AddStateEvents {
+		if ev.Type() == "m.room.name" {
+			hasRoomName = string(ev.Content()) == `{"name":"Room Name 2"}`
+		}
+	}
+	if !hasRoomName {
+		t.Errorf("Output event did not overwrite room state")
+	}
+}