Calendar: Included dates are highlighted in calendar multi-view mode (T1253076) (#28439)

Author: nikkithelegendarypokemonster

packages/devextreme/js/__internal/ui/calendar/m_calendar.range.selection.strategy.ts

@@ -117,8 +117,8 @@ class CalendarRangeSelectionStrategy extends CalendarSelectionStrategy {
 
     const { currentDate, viewsCount } = this.calendar.option();
     const isAdditionalViewDate = this.calendar._isAdditionalViewDate(currentDate);
-    const firstDateInViews = dateUtils.getFirstMonthDate(dateUtils.addDateInterval(currentDate, 'month', isAdditionalViewDate ? -2 : -1));
-    const lastDateInViews = dateUtils.getLastMonthDate(dateUtils.addDateInterval(currentDate, 'month', isAdditionalViewDate ? 1 : viewsCount));
+    const firstDateInViews = dateUtils.getFirstMonthDate(currentDate, isAdditionalViewDate ? -2 : -1);
+    const lastDateInViews = dateUtils.getLastMonthDate(currentDate, isAdditionalViewDate ? 1 : viewsCount);
 
     // @ts-expect-error
     const rangeStartDate = new Date(Math.max(firstDateInViews, startDate));

packages/devextreme/js/core/utils/date.js

@@ -466,14 +466,24 @@ const getShortDateFormat = function() {
     return 'yyyy/MM/dd';
 };
 
-const getFirstMonthDate = function(date) {
+const getFirstMonthDate = function(date, offset = 0) {
     if(!isDefined(date)) return;
-    return createDateWithFullYear(date.getFullYear(), date.getMonth(), 1);
+
+    const currentDate = new Date(date.getTime());
+    const month = currentDate.getMonth() + offset;
+    currentDate.setMonth(month);
+
+    return createDateWithFullYear(currentDate.getFullYear(), month, 1);
 };
 
-const getLastMonthDate = function(date) {
+const getLastMonthDate = function(date, offset = 0) {
     if(!isDefined(date)) return;
-    return createDateWithFullYear(date.getFullYear(), date.getMonth() + 1, 0);
+
+    const currentDate = new Date(date.getTime());
+    const month = currentDate.getMonth() + offset;
+    currentDate.setMonth(month);
+
+    return createDateWithFullYear(currentDate.getFullYear(), month + 1, 0);
 };
 
 function getFirstWeekDate(date, firstDayOfWeek) {

packages/devextreme/testing/tests/DevExpress.core/utils.date.tests.js

@@ -107,6 +107,106 @@ QUnit.test('getIntervalByString second', function(assert) {
     assert.deepEqual(this.getDateIntervalByString('second'), { seconds: 1 });
 });
 
+QUnit.module('getFirstMonthDate', () => {
+    QUnit.test('should return same month first date when offset is not provided', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 11, 15));
+
+        assert.deepEqual(newDate, new Date(2025, 11, 1));
+    });
+
+    QUnit.test('should return same month first date when offset is 0', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 11, 15), 0);
+
+        assert.deepEqual(newDate, new Date(2025, 11, 1));
+    });
+
+    QUnit.test('should decrease month correctly', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 11, 31), -1);
+
+        assert.deepEqual(newDate, new Date(2025, 10, 1));
+    });
+
+    QUnit.test('should increase month correctly', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 8, 30), 1);
+
+        assert.deepEqual(newDate, new Date(2025, 9, 1));
+    });
+
+    QUnit.test('should decrease month correctly when offset is less than -1', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 11, 15), -2);
+
+        assert.deepEqual(newDate, new Date(2025, 9, 1));
+    });
+
+    QUnit.test('should increase month correctly when offset is greater than 1', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 8, 15), 2);
+
+        assert.deepEqual(newDate, new Date(2025, 10, 1));
+    });
+
+    QUnit.test('should assign correct new date when current year is increased', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 11, 15), 1);
+
+        assert.deepEqual(newDate, new Date(2026, 0, 1));
+    });
+
+    QUnit.test('should assign correct new date when current year is decreased', function(assert) {
+        const newDate = dateUtils.getFirstMonthDate(new Date(2025, 0, 1), -1);
+
+        assert.deepEqual(newDate, new Date(2024, 11, 1));
+    });
+});
+
+QUnit.module('getLastMonthDate', () => {
+    QUnit.test('should return same month last date when offset is not provided', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 11, 15));
+
+        assert.deepEqual(newDate, new Date(2025, 11, 31));
+    });
+
+    QUnit.test('should return same month last date when offset is 0', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 11, 15), 0);
+
+        assert.deepEqual(newDate, new Date(2025, 11, 31));
+    });
+
+    QUnit.test('should decrease month correctly', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 11, 31), -1);
+
+        assert.deepEqual(newDate, new Date(2025, 10, 30));
+    });
+
+    QUnit.test('should increase month correctly', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 8, 30), 1);
+
+        assert.deepEqual(newDate, new Date(2025, 9, 31));
+    });
+
+    QUnit.test('should decrease month correctly when offset is less than -1', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 11, 15), -2);
+
+        assert.deepEqual(newDate, new Date(2025, 9, 31));
+    });
+
+    QUnit.test('should increase month correctly when offset is greater than 1', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 8, 15), 2);
+
+        assert.deepEqual(newDate, new Date(2025, 10, 30));
+    });
+
+    QUnit.test('should assign correct new date when current year is increased', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 11, 15), 1);
+
+        assert.deepEqual(newDate, new Date(2026, 0, 31));
+    });
+
+    QUnit.test('should assign correct new date when current year is decreased', function(assert) {
+        const newDate = dateUtils.getLastMonthDate(new Date(2025, 0, 1), -1);
+
+        assert.deepEqual(newDate, new Date(2024, 11, 31));
+    });
+});
+
 QUnit.test('add negative Interval number', function(assert) {
     // arrange, act
     const newNumber = dateUtils.addInterval(11, 5, true);

packages/devextreme/testing/tests/DevExpress.ui.widgets.editors/calendar.tests.js

@@ -2151,6 +2151,24 @@ QUnit.module('Options', {
                 assert.ok($cell.hasClass(CALENDAR_CELL_IN_RANGE_CLASS));
             });
 
+
+            QUnit.test(`Cells between startDate and endDate should have ${CALENDAR_CELL_IN_RANGE_CLASS} class even after currentDate runtime change (T1253076)`, function(assert) {
+                this.reinit({
+                    value: ['2025/01/01', '2025/12/31'],
+                    selectionMode: 'range',
+                    viewsCount: 2,
+                });
+
+                this.calendar.option('currentDate', new Date('2025-12-31'));
+
+                const $prevButton = $(this.$element.find(toSelector(CALENDAR_NAVIGATOR_PREVIOUS_VIEW_CLASS)));
+                $prevButton.trigger('dxclick');
+
+                const $cell = $(getCurrentViewInstance(this.calendar).$element().find('*[data-value="2025/11/01"]'));
+
+                assert.ok($cell.hasClass(CALENDAR_CELL_IN_RANGE_CLASS), 'cell is highlighted');
+            });
+
             QUnit.test('Should reselect startDate and clear endDate on click when both value are defined', function(assert) {
                 const expectedValue = [new Date('2023/01/11'), null];
                 const $cell = $(getCurrentViewInstance(this.calendar).$element().find('*[data-value="2023/01/11"]'));