Regression test for props object equality in React 19

packages/react-dom/src/__tests__/ReactComponentLifeCycle-test.js

@@ -14,6 +14,9 @@ let act;
 let React;
 let ReactDOM;
 let ReactDOMClient;
+let Scheduler;
+
+let assertLog;
 
 const clone = function (o) {
  return JSON.parse(JSON.stringify(o));
@@ -95,6 +98,9 @@ describe('ReactComponentLifeCycle', () => {
  React = require('react');
  ReactDOM = require('react-dom');
  ReactDOMClient = require('react-dom/client');
+ Scheduler = require('scheduler');
+
+ ({assertLog} = require('internal-test-utils'));
  });
 
  it('should not reuse an instance when it has been unmounted', async () => {
@@ -1387,6 +1393,112 @@ describe('ReactComponentLifeCycle', () => {
  expect(divRef.current.textContent).toBe('value: updated');
  });
 
+ it('should pass previous props to shouldComponentUpdate', async () => {
+ const root = ReactDOMClient.createRoot(document.createElement('div'));
+ let childInstance;
+
+ class App extends React.Component {
+ render() {
+ return <Child />;
+ }
+ }
+
+ class Child extends React.Component {
+ render() {
+ childInstance = this;
+ return null;
+ }
+ shouldComponentUpdate(nextProps: Object): boolean {
+ Scheduler.log(this.props === nextProps);
+ return this.props === nextProps;
+ }
+ }
+
+ await act(async () => {
+ root.render(<App />);
+ });
+
+ await act(async () => {
+ childInstance.setState({updated: true});
+ });
+
+ assertLog([true]);
+ });
+
+ it('should pass previous props to shouldComponentUpdate with defaultProps', async () => {
+ const root = ReactDOMClient.createRoot(document.createElement('div'));
+ let childInstance;
+
+ class App extends React.Component {
+ render() {
+ return <Child />;
+ }
+ }
+
+ class Child extends React.Component {
+ static defaultProps = {name: 'Alice'};
+ render() {
+ childInstance = this;
+ return null;
+ }
+ shouldComponentUpdate(nextProps: Object): boolean {
+ Scheduler.log(this.props === nextProps);
+ return this.props === nextProps;
+ }
+ }
+
+ await act(async () => {
+ root.render(<App />);
+ });
+
+ await act(async () => {
+ childInstance.setState({updated: true});
+ });
+
+ assertLog([
+ // Regression with enableRefAsProp
+ gate(flags => !flags.enableRefAsProp),
+ ]);
+ });
+
+ // @gate !disableStringRefs
+ it('should pass previous props to shouldComponentUpdate with string refs', async () => {
+ const root = ReactDOMClient.createRoot(document.createElement('div'));
+ let childInstance;
+
+ class App extends React.Component {
+ render() {
+ return <Child ref="someRef" />;
+ }
+ }
+
+ class Child extends React.Component {
+ render() {
+ childInstance = this;
+ return 'Child';
+ }
+ shouldComponentUpdate(nextProps: Object): boolean {
+ Scheduler.log(this.props === nextProps);
+ return this.props === nextProps;
+ }
+ }
+
+ await expect(async () => {
+ await act(async () => {
+ root.render(<App />);
+ });
+ }).toErrorDev('Component "App" contains the string ref "someRef".');
+
+ await act(async () => {
+ childInstance.setState({updated: true});
+ });
+
+ assertLog([
+ // Regression with enableRefAsProp
+ gate(flags => !flags.enableRefAsProp),
+ ]);
+ });
+
  it('should call getSnapshotBeforeUpdate before mutations are committed', async () => {
  const log = [];