[pickers] Keep the calendar header and content in sync when switching locale

packages/x-date-pickers/src/AdapterDayjs/AdapterDayjs.ts

@@ -513,7 +513,7 @@ export class AdapterDayjs implements MuiPickersAdapter<Dayjs, string> {
   };
 
   public startOfWeek = (value: Dayjs) => {
-    return this.adjustOffset(value.startOf('week'));
+    return this.adjustOffset(this.setLocaleToValue(value).startOf('week'));
   };
 
   public startOfDay = (value: Dayjs) => {
@@ -529,7 +529,7 @@ export class AdapterDayjs implements MuiPickersAdapter<Dayjs, string> {
   };
 
   public endOfWeek = (value: Dayjs) => {
-    return this.adjustOffset(value.endOf('week'));
+    return this.adjustOffset(this.setLocaleToValue(value).endOf('week'));
   };
 
   public endOfDay = (value: Dayjs) => {
@@ -639,9 +639,8 @@ export class AdapterDayjs implements MuiPickersAdapter<Dayjs, string> {
   };
 
   public getWeekArray = (value: Dayjs) => {
-    const cleanValue = this.setLocaleToValue(value);
-    const start = this.startOfWeek(this.startOfMonth(cleanValue));
-    const end = this.endOfWeek(this.endOfMonth(cleanValue));
+    const start = this.startOfWeek(this.startOfMonth(value));
+    const end = this.endOfWeek(this.endOfMonth(value));
 
     let count = 0;
     let current = start;

packages/x-date-pickers/src/AdapterLuxon/AdapterLuxon.ts

@@ -348,7 +348,7 @@ export class AdapterLuxon implements MuiPickersAdapter<DateTime, string> {
   };
 
   public startOfWeek = (value: DateTime) => {
-    return value.startOf('week', { useLocaleWeeks: true });
+    return this.setLocaleToValue(value).startOf('week', { useLocaleWeeks: true });
   };
 
   public startOfDay = (value: DateTime) => {
@@ -364,7 +364,7 @@ export class AdapterLuxon implements MuiPickersAdapter<DateTime, string> {
   };
 
   public endOfWeek = (value: DateTime) => {
-    return value.endOf('week', { useLocaleWeeks: true });
+    return this.setLocaleToValue(value).endOf('week', { useLocaleWeeks: true });
   };
 
   public endOfDay = (value: DateTime) => {
@@ -461,9 +461,8 @@ export class AdapterLuxon implements MuiPickersAdapter<DateTime, string> {
   };
 
   public getWeekArray = (value: DateTime) => {
-    const cleanValue = this.setLocaleToValue(value);
-    const firstDay = this.startOfWeek(this.startOfMonth(cleanValue));
-    const lastDay = this.endOfWeek(this.endOfMonth(cleanValue));
+    const firstDay = this.startOfWeek(this.startOfMonth(value));
+    const lastDay = this.endOfWeek(this.endOfMonth(value));
 
     const { days } = lastDay.diff(firstDay, 'days').toObject();
 

packages/x-date-pickers/src/AdapterMoment/AdapterMoment.ts

@@ -390,7 +390,7 @@ export class AdapterMoment implements MuiPickersAdapter<Moment, string> {
   };
 
   public startOfWeek = (value: Moment) => {
-    return value.clone().startOf('week');
+    return this.setLocaleToValue(value.clone()).startOf('week');
   };
 
   public startOfDay = (value: Moment) => {
@@ -406,7 +406,7 @@ export class AdapterMoment implements MuiPickersAdapter<Moment, string> {
   };
 
   public endOfWeek = (value: Moment) => {
-    return value.clone().endOf('week');
+    return this.setLocaleToValue(value.clone()).endOf('week');
   };
 
   public endOfDay = (value: Moment) => {
@@ -516,9 +516,8 @@ export class AdapterMoment implements MuiPickersAdapter<Moment, string> {
   };
 
   public getWeekArray = (value: Moment) => {
-    const cleanValue = this.setLocaleToValue(value);
-    const start = this.startOfWeek(this.startOfMonth(cleanValue));
-    const end = this.endOfWeek(this.endOfMonth(cleanValue));
+    const start = this.startOfWeek(this.startOfMonth(value));
+    const end = this.endOfWeek(this.endOfMonth(value));
 
     let count = 0;
     let current = start;

packages/x-date-pickers/src/DateCalendar/DayCalendar.tsx

@@ -502,7 +502,6 @@ export function DayCalendar<TDate extends PickerValidDate>(inProps: DayCalendarP
   const transitionKey = `${currentYearNumber}-${currentMonthNumber}`;
   // eslint-disable-next-line react-hooks/exhaustive-deps
   const slideNodeRef = React.useMemo(() => React.createRef<HTMLDivElement>(), [transitionKey]);
-  const startOfCurrentWeek = utils.startOfWeek(now);
 
   const focusableDay = React.useMemo<TDate | null>(() => {
     const startOfMonth = utils.startOfMonth(currentMonth);
@@ -574,7 +573,7 @@ export function DayCalendar<TDate extends PickerValidDate>(inProps: DayCalendarP
             key={i.toString()}
             variant="caption"
             role="columnheader"
-            aria-label={utils.format(utils.addDays(startOfCurrentWeek, i), 'weekday')}
+            aria-label={utils.format(weekday, 'weekday')}
             className={classes.weekDayLabel}
           >
             {dayOfWeekFormatter(weekday)}

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

@@ -1,4 +1,5 @@
 import * as React from 'react';
+import moment, { Moment } from 'moment';
 import { DateCalendar } from '@mui/x-date-pickers/DateCalendar';
 
 <DateCalendar />;
@@ -8,3 +9,13 @@ import { DateCalendar } from '@mui/x-date-pickers/DateCalendar';
 <DateCalendar value={new Date()} />;
 
 <DateCalendar value={null} />;
+
+// External components are generic as well
+<DateCalendar<Moment>
+  view="day"
+  views={['day']}
+  value={moment()}
+  minDate={moment()}
+  maxDate={moment()}
+  onChange={(date) => date?.format()}
+/>;

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

@@ -1,11 +1,14 @@
 import * as React from 'react';
 import { expect } from 'chai';
-import { screen } from '@mui/internal-test-utils';
-import { DateCalendar } from '@mui/x-date-pickers/DateCalendar';
-import { createPickerRenderer, AdapterName } from 'test/utils/pickers';
-import { he } from 'date-fns/locale';
+import { screen, createRenderer } from '@mui/internal-test-utils';
+import { DateCalendar, dayCalendarClasses } from '@mui/x-date-pickers/DateCalendar';
+import { LocalizationProvider } from '@mui/x-date-pickers/LocalizationProvider';
+import { createPickerRenderer, AdapterName, availableAdapters } from 'test/utils/pickers';
+import { he, fr } from 'date-fns/locale';
 import 'dayjs/locale/he';
+import 'dayjs/locale/fr';
 import 'moment/locale/he';
+import 'moment/locale/fr';
 
 const ADAPTERS_TO_USE: AdapterName[] = ['date-fns', 'dayjs', 'luxon', 'moment'];
 
@@ -17,11 +20,33 @@ describe('<DateCalendar /> - localization', () => {
         adapterName,
       });
 
+      const { render: renderWithoutWrapper } = createRenderer();
+
       it('should display correct week day labels in Hebrew locale ', () => {
         render(<DateCalendar />);
 
         expect(screen.getByText('א')).toBeVisible();
       });
+
+      it('should correctly switch between locale with week starting in Monday and week starting in Sunday', () => {
+        const { setProps } = renderWithoutWrapper(
+          <LocalizationProvider dateAdapter={availableAdapters[adapterName]}>
+            <DateCalendar reduceAnimations />
+          </LocalizationProvider>,
+        );
+
+        expect(document.querySelector(`.${dayCalendarClasses.weekDayLabel}`)!.ariaLabel).to.equal(
+          'Sunday',
+        );
+
+        setProps({
+          adapterLocale: adapterName === 'date-fns' ? fr : 'fr',
+        });
+
+        expect(document.querySelector(`.${dayCalendarClasses.weekDayLabel}`)!.ariaLabel).to.equal(
+          'lundi',
+        );
+      });
     });
   });
 });