fix(datetime): prefer wheel sets working value on confirmation

core/src/components/datetime/datetime.tsx

@@ -500,7 +500,16 @@ export class Datetime implements ComponentInterface {
     if (activeParts !== undefined || !isCalendarPicker) {
       const activePartsIsArray = Array.isArray(activeParts);
       if (activePartsIsArray && activeParts.length === 0) {
-        this.setValue(undefined);
+        if (this.preferWheel) {
+          /**
+           * If the datetime is using a wheel picker, but there
+           * is no active parts, then the user has confirmed the
+           * initial value (working parts) presented to them.
+           */
+          this.setValue(convertDataToISO(this.workingParts));
+        } else {
+          this.setValue(undefined);
+        }
       } else {
         this.setValue(convertDataToISO(activeParts));
       }

core/src/components/datetime/test/prefer-wheel/datetime.spec.ts

@@ -0,0 +1,31 @@
+import { newSpecPage } from '@stencil/core/testing';
+
+import { Datetime } from '../../datetime';
+
+describe('datetime: preferWheel', () => {
+  beforeEach(() => {
+    const mockIntersectionObserver = jest.fn();
+    mockIntersectionObserver.mockReturnValue({
+      observe: () => null,
+      unobserve: () => null,
+      disconnect: () => null,
+    });
+    global.IntersectionObserver = mockIntersectionObserver;
+  });
+
+  it('should select the working day when clicking the confirm button', async () => {
+    const page = await newSpecPage({
+      components: [Datetime],
+      html: '<ion-datetime prefer-wheel="true" max="2021" show-default-buttons="true"></ion-datetime>',
+    });
+
+    const datetime = page.body.querySelector<HTMLIonDatetimeElement>('ion-datetime')!;
+    const confirmButton = datetime.shadowRoot!.querySelector<HTMLIonButtonElement>('#confirm-button')!;
+
+    confirmButton.click();
+
+    await page.waitForChanges();
+
+    expect(datetime.value).toBe('2021-12-31T23:59:00');
+  });
+});