Reduce flake on edit mock test

ts/test-mock/helpers.ts

@@ -1,6 +1,8 @@
 // Copyright 2023 Signal Messenger, LLC
 // SPDX-License-Identifier: AGPL-3.0-only
 
+import type { Locator } from 'playwright';
+
 export function bufferToUuid(buffer: Buffer): string {
   const hex = buffer.toString('hex');
 
@@ -12,3 +14,21 @@ export function bufferToUuid(buffer: Buffer): string {
     hex.substring(20),
   ].join('-');
 }
+
+export async function type(input: Locator, text: string): Promise<void> {
+  let currentValue = '';
+
+  try {
+    currentValue = await input.inputValue();
+  } catch (e) {
+    // if input is actually not an input (e.g. contenteditable)
+    currentValue = (await input.textContent()) ?? '';
+  }
+
+  // Type with a reasonably human delay
+  await input.type(text, { delay: 100 });
+
+  // Wait to ensure that the input (and react state controlling it) has actually
+  // updated with the right value
+  await input.locator(`:text("${currentValue}${text}")`).waitFor();
+}

ts/test-mock/messaging/edit_test.ts

@@ -16,6 +16,7 @@ import { drop } from '../../util/drop';
 import { strictAssert } from '../../util/assert';
 import { generateAci } from '../../types/ServiceId';
 import { IMAGE_GIF } from '../../types/MIME';
+import { type } from '../helpers';
 
 export const debug = createDebug('mock:test:edit');
 
@@ -505,7 +506,7 @@ describe('editing', function (this: Mocha.Suite) {
           .click();
         await page.getByRole('menuitem', { name: 'Edit' }).click();
         const input = await app.waitForEnabledComposer();
-        await input.type(additionalText);
+        await type(input, additionalText);
         await input.press('Enter');
       }
       const { contacts, desktop } = bootstrap;