Calendar: should not throw any errors if value is empty string (T1257679) (#28359)

Co-authored-by: EugeniyKiyashko <[email protected]>

Author: nikkithelegendarypokemonster

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

@@ -27,7 +27,13 @@ class CalendarSingleSelectionStrategy extends CalendarSelectionStrategy {
   }
 
   getDefaultCurrentDate() {
-    return this.dateOption('value');
+    const date = this.dateOption('value');
+
+    if (date === '') {
+      return new Date();
+    }
+
+    return date;
   }
 
   restoreValue(): void {

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

@@ -325,6 +325,18 @@ QUnit.module('Navigator integration', {
         assert.equal($navigatorCaption.text(), 'July 2015', 'navigator caption is correct');
     });
 
+    QUnit.test('should not throw any errors if value on initialization is empty string (T1257679)', function(assert) {
+        try {
+            this.reinit({
+                value: ''
+            });
+        } catch(e) {
+            assert.ok(false, `error: ${e.message}`);
+        } finally {
+            assert.ok(true, 'there is no error');
+        }
+    });
+
     QUnit.test('navigator caption should be changed during swipe', function(assert) {
         const $element = this.$element;
         const $navigatorCaption = this.$navigatorCaption;

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

@@ -69,6 +69,8 @@ const LIST_CLASS = 'dx-list';
 const CLEAR_BUTTON_AREA_CLASS = 'dx-clear-button-area';
 const CALENDAR_CELL_CLASS = 'dx-calendar-cell';
 const CALENDAR_TODAY_BUTTON_CLASS = 'dx-calendar-today-button';
+const CALENDAR_CAPTION_BUTTON_CLASS = 'dx-calendar-caption-button';
+const CALENDAR_NAVIGATOR_NEXT_VIEW_CLASS = 'dx-calendar-navigator-next-view';
 const CALENDAR_NAVIGATOR_PREVIOUS_VIEW_CLASS = 'dx-calendar-navigator-previous-view';
 const DROPDOWNEDITOR_OVERLAY_CLASS = 'dx-dropdowneditor-overlay';
 const NUMBERBOX_CLASS = 'dx-numberbox';
@@ -6107,6 +6109,24 @@ QUnit.module('DateBox number and string value support', {
         });
     });
 
+    QUnit.test('should not throw any errors after clicking on the navigator caption button if the value is an empty string (T1257679)', function(assert) {
+        const dateBox = $('#dateBox').dxDateBox({
+            type: 'date',
+            pickerType: 'calendar',
+            value: '',
+            opened: true,
+        }).dxDateBox('instance');
+
+        try {
+            const $navigatorCaptionButton = dateBox._popup.$wrapper().find(`.${CALENDAR_CAPTION_BUTTON_CLASS}`);
+
+            $($navigatorCaptionButton).trigger('dxclick');
+        } catch(e) {
+            assert.ok(false, `error: ${e.message}`);
+        } finally {
+            assert.ok(true, 'there is no error');
+        }
+    });
 });
 
 testModule('native picker', function() {