Fix

Author: flaviendelangle

packages/x-date-pickers/src/DateCalendar/tests/DateCalendar.test.tsx

@@ -638,7 +638,8 @@ describe('<DateCalendar />', () => {
 
       const renderCountBeforeChange = RenderCount.callCount;
       fireEvent.click(screen.getByRole('gridcell', { name: '2' }));
-      expect(RenderCount.callCount - renderCountBeforeChange).to.equal(4); // 2 render * 2 days
+      // 2 render (one to update tabIndex + autoFocus, one to update selection) * 2 days * 2 (because dev mode)
+      expect(RenderCount.callCount - renderCountBeforeChange).to.equal(8);
     });
   });
 });

packages/x-date-pickers/src/PickersDay/PickersDay.tsx

@@ -231,6 +231,22 @@ const PickersDayFiller = styled('div', {
 
 const noop = () => {};
 
+const useUpdateTracking = (props) => {
+  const oldProps = React.useRef(props);
+
+  React.useEffect(() => {
+    // eslint-disable-next-line no-console
+    console.log(
+      props.day.toString(),
+      Object.keys(props)
+        .map((key) => ({ key, current: props[key], old: oldProps.current[key] }))
+        .filter(({ old, current }) => old !== current),
+    );
+
+    oldProps.current = props;
+  });
+};
+
 type PickersDayComponent = ((
   props: PickersDayProps & React.RefAttributes<HTMLButtonElement>,
 ) => React.JSX.Element) & { propTypes?: any };
@@ -270,6 +286,8 @@ const PickersDayRaw = React.forwardRef(function PickersDay(
     ...other
   } = props;
 
+  // useUpdateTracking(props);
+
   const ownerState = {
     ...props,
     autoFocus,