test: add typing-in-a-large-document perf baseline

Author: christianhg

packages/editor/tests/performance.test.tsx

@@ -1,5 +1,6 @@
 import React from 'react'
 import {describe, expect, test, vi} from 'vitest'
+import {userEvent} from 'vitest/browser'
 import {defineSchema} from '../src'
 import {InternalEditorEngineRefPlugin} from '../src/plugins/plugin.internal.editor-engine-ref'
 import {NodePlugin} from '../src/plugins/plugin.node'
@@ -36,6 +37,53 @@ describe('Performance', () => {
       console.warn(`Inserted 1000 blocks in ${duration.toFixed(2)}ms`)
     })
 
+    test('Typing 20 characters in a 1000-block document', async () => {
+      const {editor, locator} = await createTestEditor()
+
+      editor.send({
+        type: 'insert.blocks',
+        blocks: Array.from({length: 1000}, (_, i) => ({
+          _type: 'block',
+          _key: `b${i}`,
+          children: [
+            {_type: 'span', _key: `s${i}`, text: `block ${i}`, marks: []},
+          ],
+          markDefs: [],
+          style: 'normal',
+        })),
+        placement: 'auto',
+      })
+
+      await vi.waitFor(() => {
+        expect(editor.getSnapshot().context.value.length).toBe(1000)
+
+        expect(locator.getByText('block 999')).toBeInTheDocument()
+      })
+
+      await userEvent.click(locator.getByText('block 500'))
+
+      const start = performance.now()
+
+      await userEvent.keyboard('performance!!!!!!!!!')
+
+      await vi.waitFor(() => {
+        const children = (
+          editor.getSnapshot().context.value[500] as {
+            children?: Array<{text?: string}>
+          }
+        ).children
+        expect(
+          children?.some((child) => child.text?.includes('performance')),
+        ).toBe(true)
+      })
+
+      const duration = performance.now() - start
+
+      console.warn(
+        `Typed 20 characters in a 1000-block document in ${duration.toFixed(2)}ms`,
+      )
+    })
+
     test('Inserting 1000 blocks before an existing block', async () => {
       const {editor, locator} = await createTestEditor()