Scheduler a11y: Fix data cell header contrast (component level) (#28368)

Author: tongsonbarbs

apps/demos/testing/etalons/Scheduler-Adaptability (fluent.blue.light).png

@@ -0,0 +1,35 @@
+import Scheduler from 'devextreme-testcafe-models/scheduler';
+import { createScreenshotsComparer } from 'devextreme-screenshot-comparer';
+import { createWidget } from '../../../helpers/createWidget';
+import url from '../../../helpers/getPageUrl';
+import { changeTheme } from '../../../helpers/changeTheme';
+import { Themes } from '../../../helpers/themes';
+
+fixture.disablePageReloads`a11y - contrast`
+  .page(url(__dirname, '../../container.html'));
+
+[
+  Themes.genericLight,
+  Themes.genericDark,
+  Themes.fluentBlue,
+  Themes.fluentBlueDark,
+].forEach((theme) => {
+  test(`Scheduler a11y: Insufficient contrast of day numbers in the MonthView (${theme})`, async (t) => {
+    const scheduler = new Scheduler('#container');
+    const { takeScreenshot, compareResults } = createScreenshotsComparer(t);
+
+    await t
+      .expect(await takeScreenshot(`month_day_number_contrast-${theme}`, scheduler.element))
+      .ok()
+      .expect(compareResults.isValid())
+      .ok(compareResults.errorMessages());
+  }).before(async () => {
+    await createWidget('dxScheduler', {
+      dataSource: [],
+      currentView: 'month',
+      currentDate: new Date(2020, 10, 25),
+    });
+  }).after(async () => {
+    await changeTheme(Themes.genericLight);
+  });
+});