fix(datetime): account for 12AM with min times and 12 hour format

core/src/components/datetime/test/data.spec.ts

@@ -63,7 +63,7 @@ describe('generateTime()', () => {
     };
     const { hours, minutes } = generateTime(today, 'h12', min);
 
-    expect(hours.length).toEqual(11);
+    expect(hours.length).toEqual(10);
     expect(minutes.length).toEqual(60);
   });
   it('should not filter according to min if not on reference day', () => {
@@ -103,7 +103,7 @@ describe('generateTime()', () => {
     };
     const { hours, minutes } = generateTime(today, 'h12', undefined, max);
 
-    expect(hours.length).toEqual(7);
+    expect(hours.length).toEqual(8);
     expect(minutes.length).toEqual(45);
   });
   it('should not filter according to min if not on reference day', () => {

core/src/components/datetime/test/format.spec.ts

@@ -57,7 +57,7 @@ describe('getMonthAndDay()', () => {
 describe('getFormattedHour()', () => {
   it('should only add padding if using 24 hour time', () => {
     expect(getFormattedHour(0, true)).toEqual('00');
-    expect(getFormattedHour(0, false)).toEqual('0');
+    expect(getFormattedHour(0, false)).toEqual('12');
 
     expect(getFormattedHour(10, true)).toEqual('10');
     expect(getFormattedHour(10, false)).toEqual('10');

core/src/components/datetime/test/minmax/datetime.e2e.ts

@@ -188,4 +188,50 @@ test.describe('datetime: minmax', () => {
 
     await expect(datetimeMonthDidChange).toHaveReceivedEventTimes(1);
   });
+
+  test('should not include 12AM when minimum is greater than 12AM', async ({ page, skip }) => {
+    skip.rtl();
+
+    test.info().annotations.push({
+      type: 'issue',
+      description: 'https://github.com/ionic-team/ionic-framework/issues/25183',
+    });
+
+    await page.setContent(`
+      <ion-datetime
+        presentation="time"
+        min="2022-04-25T08:30:00"
+        max="2022-04-25T21:30:00"
+        value="2022-04-25T08:30:00"
+      ></ion-datetime>
+    `);
+
+    const hourPickerItems = page.locator(
+      'ion-datetime ion-picker-column-internal:first-of-type .picker-item:not(.picker-item-empty)'
+    );
+    await expect(hourPickerItems).toHaveText(['8', '9', '10', '11']);
+  });
+
+  test('should include 12PM when minimum is greater than 12', async ({ page, skip }) => {
+    skip.rtl();
+
+    test.info().annotations.push({
+      type: 'issue',
+      description: 'https://github.com/ionic-team/ionic-framework/issues/25183',
+    });
+
+    await page.setContent(`
+      <ion-datetime
+        locale="en-US"
+        presentation="time"
+        min="2022-07-29T08:00:00"
+        value="2022-07-29T12:00:00"
+      ></ion-datetime>
+    `);
+
+    const hourPickerItems = page.locator(
+      'ion-datetime ion-picker-column-internal:first-of-type .picker-item:not(.picker-item-empty)'
+    );
+    await expect(hourPickerItems).toHaveText(['12', '1', '2', '3', '4', '5', '6', '7', '8', '9', '10', '11']);
+  });
 });

core/src/components/datetime/utils/data.ts

@@ -44,7 +44,7 @@ const minutes = [
   0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31,
   32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59,
 ];
-const hour12 = [12, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
+const hour12 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
 const hour23 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23];
 
 /**

core/src/components/datetime/utils/format.ts

@@ -49,16 +49,26 @@ export const addTimePadding = (value: number): string => {
 };
 
 /**
- * Formats the hour value so that it
- * is always 2 digits. Only applies
- * if using 12 hour format.
+ * Formats 24 hour times so that
+ * it always has 2 digits. For
+ * 12 hour times it ensures that
+ * hour 0 is formatted as '12'.
  */
 export const getFormattedHour = (hour: number, use24Hour: boolean): string => {
-  if (!use24Hour) {
-    return hour.toString();
+  if (use24Hour) {
+    return addTimePadding(hour);
   }
 
-  return addTimePadding(hour);
+  /**
+   * If using 12 hour
+   * format, make sure hour
+   * 0 is formatted as '12'.
+   */
+  if (hour === 0) {
+    return '12';
+  }
+
+  return hour.toString();
 };
 
 /**