From 7859989c991a38ce7ffb6966acfed3f2f23f522c Mon Sep 17 00:00:00 2001
From: Lena Morita <lena@jaguchi.com>
Date: Fri, 12 Nov 2021 04:35:04 +0900
Subject: [PATCH] Add test for multiplayer undo

---
 .../use-yjs/__test-helpers__/utils.js         | 17 +++++
 .../use-yjs/__tests__/undo.js                 | 68 +++++++++++++++++--
 2 files changed, 80 insertions(+), 5 deletions(-)

diff --git a/src/components/collaborative-editing/use-yjs/__test-helpers__/utils.js b/src/components/collaborative-editing/use-yjs/__test-helpers__/utils.js
index fc68807d8..3b47634f5 100644
--- a/src/components/collaborative-editing/use-yjs/__test-helpers__/utils.js
+++ b/src/components/collaborative-editing/use-yjs/__test-helpers__/utils.js
@@ -1,3 +1,8 @@
+/**
+ * External dependencies
+ */
+import { waitFor } from '@testing-library/react';
+
 /**
  * Helper to generate mock transport modules for an isolated channel.
  *
@@ -47,3 +52,15 @@ export function getTransports( count ) {
 		.fill( null )
 		.map( () => mockTransport() );
 }
+
+/**
+ * Emulate a pause between typing events for Yjs to make a new undo stack item.
+ *
+ * Requires jest.useRealTimers().
+ *
+ * @param {import('@testing-library/dom').Screen} screen
+ */
+export async function pauseTyping( screen ) {
+	screen.getAllByRole( 'document' ).forEach( ( el ) => el.blur() );
+	await waitFor( () => new Promise( ( resolve ) => setTimeout( resolve, 550 ) ) );
+}
diff --git a/src/components/collaborative-editing/use-yjs/__tests__/undo.js b/src/components/collaborative-editing/use-yjs/__tests__/undo.js
index 7bed5c965..1870aff56 100644
--- a/src/components/collaborative-editing/use-yjs/__tests__/undo.js
+++ b/src/components/collaborative-editing/use-yjs/__tests__/undo.js
@@ -1,14 +1,14 @@
 /**
  * External dependencies
  */
-import { render, screen, waitFor } from '@testing-library/react';
+import { act, render, screen, waitFor, within } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 
 /**
  * Internal dependencies
  */
 import IsolatedBlockEditor, { CollaborativeEditing } from '../../../../index';
-import { getTransports } from '../__test-helpers__/utils';
+import { getTransports, pauseTyping } from '../__test-helpers__/utils';
 
 const collabSettings = {
 	enabled: true,
@@ -44,9 +44,8 @@ describe( 'CollaborativeEditing: Undo/Redo', () => {
 		userEvent.keyboard( 'hello' );
 		expect( screen.getByRole( 'document', { name: 'Paragraph block' } ) ).toHaveTextContent( 'hello' );
 
-		// Emulate pause for Yjs to make a new undo stack item
-		screen.getByRole( 'document', { name: 'Paragraph block' } ).blur();
-		await waitFor( () => new Promise( ( resolve ) => setTimeout( resolve, 500 ) ) );
+		await pauseTyping( screen );
+
 		userEvent.click( screen.getByRole( 'document', { name: 'Paragraph block' } ) );
 
 		userEvent.keyboard( 'world' );
@@ -73,4 +72,63 @@ describe( 'CollaborativeEditing: Undo/Redo', () => {
 		userEvent.click( screen.getByRole( 'button', { name: 'Redo' } ) );
 		expect( screen.getByRole( 'document', { name: 'Paragraph block' } ) ).toHaveTextContent( 'helloworld' );
 	} );
+
+	it( 'should only undo/redo own edits', async () => {
+		const [ transport1, transport2 ] = getTransports( 2 );
+		const [ onSave1, onSave2 ] = [ jest.fn(), jest.fn() ];
+		await act( async () => {
+			render(
+				<>
+					<div data-testid="alice">
+						<IsolatedBlockEditor settings={ {} } onSaveContent={ onSave1 }>
+							<CollaborativeEditing
+								settings={ { ...collabSettings, transport: transport1, username: 'Alice' } }
+							/>
+						</IsolatedBlockEditor>
+					</div>
+					<div data-testid="bob">
+						<IsolatedBlockEditor settings={ {} } onSaveContent={ onSave2 }>
+							<CollaborativeEditing
+								settings={ { ...collabSettings, transport: transport2, username: 'Bob' } }
+							/>
+						</IsolatedBlockEditor>
+					</div>
+				</>
+			);
+		} );
+		const aliceScreen = within( screen.getByTestId( 'alice' ) );
+		const bobScreen = within( screen.getByTestId( 'bob' ) );
+
+		userEvent.click( aliceScreen.getByText( /^Start writing.+/ ) );
+		userEvent.keyboard( 'alice:{Enter}' );
+
+		await pauseTyping( aliceScreen );
+
+		userEvent.click( bobScreen.getAllByRole( 'document' )[ 1 ] );
+		userEvent.keyboard( 'bobby:' );
+
+		userEvent.click( bobScreen.getByRole( 'button', { name: 'Undo' } ) );
+		expect( screen.queryByText( 'bobby:' ) ).toBe( null );
+
+		userEvent.click( bobScreen.getAllByRole( 'document' )[ 1 ] );
+		userEvent.keyboard( 'bob:' );
+
+		await pauseTyping( bobScreen );
+
+		userEvent.click( aliceScreen.getAllByRole( 'document' )[ 0 ] );
+		userEvent.keyboard( 'hello' );
+
+		userEvent.click( bobScreen.getByRole( 'button', { name: 'Undo' } ) );
+		expect( screen.queryByText( 'bob:' ) ).toBe( null );
+
+		expect( screen.getByText( 'alice:hello' ) ).toBeInTheDocument();
+		userEvent.click( aliceScreen.getByRole( 'button', { name: 'Undo' } ) );
+		expect( screen.queryByText( 'hello' ) ).toBe( null );
+
+		userEvent.click( bobScreen.getByRole( 'button', { name: 'Redo' } ) );
+		expect( screen.getByText( 'bob:' ) ).toBeInTheDocument();
+
+		// Both editors should have the same content
+		expect( onSave1 ).toHaveBeenLastCalledWith( onSave2.mock.calls[ onSave2.mock.calls.length - 1 ][ 0 ] );
+	} );
 } );