Fix "[object Promise]" appearing in HTML exports (#9975)

Fixes https://github.com/vector-im/element-web/issues/24272

test/components/views/dialogs/MessageEditHistoryDialog-test.tsx

@@ -0,0 +1,83 @@
+/*
+Copyright 2023 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.
+*/
+
+import React from "react";
+import { render, RenderResult } from "@testing-library/react";
+import { EventType, MatrixEvent } from "matrix-js-sdk/src/matrix";
+
+import type { MatrixClient } from "matrix-js-sdk/src/matrix";
+import { flushPromises, mkMessage, stubClient } from "../../../test-utils";
+import MessageEditHistoryDialog from "../../../../src/components/views/dialogs/MessageEditHistoryDialog";
+
+describe("<MessageEditHistory />", () => {
+    const roomId = "!aroom:example.com";
+    let client: jest.Mocked<MatrixClient>;
+    let event: MatrixEvent;
+
+    beforeEach(() => {
+        client = stubClient() as jest.Mocked<MatrixClient>;
+        event = mkMessage({
+            event: true,
+            user: "@user:example.com",
+            room: "!room:example.com",
+            msg: "My Great Message",
+        });
+    });
+
+    async function renderComponent(): Promise<RenderResult> {
+        const result = render(<MessageEditHistoryDialog mxEvent={event} onFinished={jest.fn()} />);
+        await flushPromises();
+        return result;
+    }
+
+    function mockEdits(...edits: { msg: string; ts: number | undefined }[]) {
+        client.relations.mockImplementation(() =>
+            Promise.resolve({
+                events: edits.map(
+                    (e) =>
+                        new MatrixEvent({
+                            type: EventType.RoomMessage,
+                            room_id: roomId,
+                            origin_server_ts: e.ts,
+                            content: {
+                                body: e.msg,
+                            },
+                        }),
+                ),
+            }),
+        );
+    }
+
+    it("should match the snapshot", async () => {
+        mockEdits({ msg: "My Great Massage", ts: 1234 });
+
+        const { container } = await renderComponent();
+
+        expect(container).toMatchSnapshot();
+    });
+
+    it("should support events with ", async () => {
+        mockEdits(
+            { msg: "My Great Massage", ts: undefined },
+            { msg: "My Great Massage?", ts: undefined },
+            { msg: "My Great Missage", ts: undefined },
+        );
+
+        const { container } = await renderComponent();
+
+        expect(container).toMatchSnapshot();
+    });
+});