Should open new 1:1 chat room after leaving the old one

cypress/e2e/one-to-one-chat/one-to-one-chat.spec.ts

@@ -0,0 +1,60 @@
+/*
+Copyright 2022 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+/// <reference types="cypress" />
+
+import { SynapseInstance } from "../../plugins/synapsedocker";
+import type { Credentials } from "../../support/synapse";
+
+describe("1:1 chat room", () => {
+    let synapse: SynapseInstance;
+    let user2: Credentials;
+
+    const username = "user1234";
+    const password = "p4s5W0rD";
+
+    beforeEach(() => {
+        cy.startSynapse("default").then((data) => {
+            synapse = data;
+
+            cy.initTestUser(synapse, "Jeff");
+            cy.registerUser(synapse, username, password).then((credentials) => {
+                user2 = credentials;
+                cy.visit(`/#/user/${user2.userId}?action=chat`);
+            });
+        });
+    });
+
+    afterEach(() => {
+        cy.stopSynapse(synapse);
+    });
+
+    it("should open new 1:1 chat room after leaving the old one", () => {
+        // leave 1:1 chat room
+        cy.contains(".mx_RoomHeader_nametext", username).click();
+        cy.contains('[role="menuitem"]', "Leave").click();
+        cy.get('[data-testid="dialog-primary-button"]').click();
+
+        // wait till the room was left
+        cy.get('[role="group"][aria-label="Historical"]').within(() => {
+            cy.contains(".mx_RoomTile", username);
+        });
+
+        // open new 1:1 chat room
+        cy.visit(`/#/user/${user2.userId}?action=chat`);
+        cy.contains(".mx_RoomHeader_nametext", username);
+    });
+});

src/components/structures/MatrixChat.tsx

@@ -138,6 +138,7 @@ import { VoiceBroadcastResumer } from "../../voice-broadcast";
 import GenericToast from "../views/toasts/GenericToast";
 import { Linkify } from "../views/elements/Linkify";
 import RovingSpotlightDialog, { Filter } from "../views/dialogs/spotlight/SpotlightDialog";
+import { findDMForUser } from "../../utils/dm/findDMForUser";
 
 // legacy export
 export { default as Views } from "../../Views";
@@ -1098,13 +1099,12 @@ export default class MatrixChat extends React.PureComponent<IProps, IState> {
         // TODO: Immutable DMs replaces this
 
         const client = MatrixClientPeg.get();
-        const dmRoomMap = new DMRoomMap(client);
-        const dmRooms = dmRoomMap.getDMRoomsForUserId(userId);
+        const dmRoom = findDMForUser(client, userId);
 
-        if (dmRooms.length > 0) {
+        if (dmRoom) {
             dis.dispatch<ViewRoomPayload>({
                 action: Action.ViewRoom,
-                room_id: dmRooms[0],
+                room_id: dmRoom.roomId,
                 metricsTrigger: "MessageUser",
             });
         } else {