Concurrent Mode test for uMS render mutation

Same test as the one added in facebook#20665, but for Concurrent Mode.

packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js

@@ -1730,6 +1730,53 @@ describe('useMutableSource', () => {
  param => param.version,
  );
 
+ let mutatedValueInRender = 0;
+ function MutateDuringRead() {
+ const value = useMutableSource(
+ mutableSource,
+ defaultGetSnapshot,
+ defaultSubscribe,
+ );
+ Scheduler.unstable_yieldValue('MutateDuringRead:' + value);
+ // Note that mutating an exeternal value during render is a side effect and is not supported.
+ source.value = mutatedValueInRender++;
+ return null;
+ }
+
+ expect(() => {
+ expect(() => {
+ act(() => {
+ ReactNoop.render(<MutateDuringRead />);
+ });
+ }).toThrow(
+ 'Cannot read from mutable source during the current render without tearing. This may be a bug in React. Please file an issue.',
+ );
+ }).toWarnDev([
+ // Warns twice because of the retry-on-error render pass. Should
+ // consider only warning during the first attempt, not during the
+ // retry. Or maybe vice versa.
+ 'A mutable source was mutated while the MutateDuringRead component was rendering. This is not supported. ' +
+ 'Move any mutations into event handlers or effects.\n' +
+ ' in MutateDuringRead (at **)',
+ 'A mutable source was mutated while the MutateDuringRead component was rendering. This is not supported. ' +
+ 'Move any mutations into event handlers or effects.\n' +
+ ' in MutateDuringRead (at **)',
+ ]);
+
+ expect(Scheduler).toHaveYielded([
+ 'MutateDuringRead:initial',
+ 'MutateDuringRead:0',
+ ]);
+ });
+
+ // @gate experimental
+ it('should throw if a mutable source is mutated during render (legacy mode)', () => {
+ const source = createSource('initial');
+ const mutableSource = createMutableSource(
+ source,
+ param => param.version,
+ );
+
  function MutateDuringRead() {
  const value = useMutableSource(
  mutableSource,