`TestRoomCreationReportsEventsToMyself` tests unspecified behaviour

[timedoutuk]

complement/tests/csapi/rooms_state_test.go

Lines 90 to 108 in 1a2baac

	// sytest: Setting state twice is idempotent
	t.Run("Setting state twice is idempotent", func(t *testing.T) {
	t.Parallel()
	stateEvent := b.Event{
	Type: "a.test.state.type",
	StateKey: b.Ptr(""),
	Content: map[string]interface{}{
	"a_key": "a_value",
	},
	}
	firstID := alice.SendEventSynced(t, roomID, stateEvent)
	secondID := alice.SendEventSynced(t, roomID, stateEvent)
	if firstID != secondID {
	t.Fatalf("Both Event IDs from supposedly-idempotent state-setting differ, %s != %s", firstID, secondID)
	}
	})

This behaviour is not written anywhere in the specification and is technically incorrect behaviour considering there is no transaction ID for setting state (which removes the idempotency guarantee)

[timedoutuk]

Joining room twice is idempotent suffers this same problem:

complement/tests/csapi/rooms_state_test.go

Lines 110 to 138 in 1a2baac

	// sytest: Joining room twice is idempotent
	t.Run("Joining room twice is idempotent", func(t *testing.T) {
	t.Parallel()
	roomID := bob.MustCreateRoom(t, map[string]interface{}{
	"visibility": "public",
	"preset": "public_chat",
	})
	alice.MustJoinRoom(t, roomID, nil)
	alice.MustSyncUntil(t, client.SyncReq{}, client.SyncJoinedTo(alice.UserID, roomID))
	firstID := *getEventIdForState(t, alice, roomID, "m.room.member", alice.UserID)
	alice.MustJoinRoom(t, roomID, nil)
	// Unfortunately there is no way to definitively wait
	// for a 'potentially false second join event' without
	// also failing the test on timeout, with the current APIs.
	//
	// So we take a conservative estimate of a 5-second sleep delay
	// before we check on the server again.
	time.Sleep(5 * time.Second)
	secondID := *getEventIdForState(t, alice, roomID, "m.room.member", alice.UserID)
	if firstID != secondID {
	t.Fatalf("Both Event IDs from supposedly-idempotent room joins differ, %s != %s", firstID, secondID)
	}

Neither /_matrix/client/v3/join/{roomIdOrAlias} nor /_matrix/client/v3/rooms/{roomId}/join state that multiple calls have to be idempotent.