Scheduler: fix days duplication in workspace (T1252028) (#30427)

Co-authored-by: Vladimir Bushmanov <[email protected]>

Author: Ambrozy

packages/devextreme/jest.config.js

@@ -1,6 +1,6 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} **/
 module.exports = {
-    testEnvironment: 'jsdom',
+    testEnvironment: '<rootDir>/jsdom-with-timezone.js',
     roots: ['<rootDir>/js'],
     moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],
     moduleNameMapper: {

packages/devextreme/js/__internal/scheduler/__tests__/__mock__/m_mock_scheduler.ts

@@ -0,0 +1,30 @@
+import { jest } from '@jest/globals';
+import DOMComponent from '@ts/core/widget/dom_component';
+
+import SchedulerWorkSpace from '../../workspaces/m_work_space';
+
+export const setupSchedulerTestEnvironment = ({
+  cellWidth,
+  cellHeight,
+} = {
+  cellWidth: 250,
+  cellHeight: 80,
+}): void => {
+  (DOMComponent.prototype as any)._isVisible = jest.fn().mockReturnValue(true);
+  SchedulerWorkSpace.prototype._createCrossScrollingConfig = () => ({
+    direction: 'both',
+    onScroll: jest.fn(),
+    onEnd: jest.fn(),
+  });
+  Element.prototype.getBoundingClientRect = jest.fn(() => ({
+    width: cellWidth,
+    height: cellHeight,
+    top: 0,
+    left: 0,
+    bottom: cellHeight,
+    right: cellWidth,
+    x: 0,
+    y: 0,
+    toJSON: (): void => {},
+  }));
+};