fix(datetime): passing min/max no longer errors on missing date information

core/src/components/datetime/datetime.tsx

@@ -46,7 +46,15 @@ import {
   getPreviousYear,
   getStartOfWeek,
 } from './utils/manipulation';
-import { clampDate, convertToArrayOfNumbers, getPartsFromCalendarDay, parseAmPm, parseDate } from './utils/parse';
+import {
+  clampDate,
+  convertToArrayOfNumbers,
+  getPartsFromCalendarDay,
+  parseAmPm,
+  parseDate,
+  parseMaxParts,
+  parseMinParts,
+} from './utils/parse';
 import {
   getCalendarDayState,
   isDayDisabled,
@@ -784,37 +792,24 @@ export class Datetime implements ComponentInterface {
   };
 
   private processMinParts = () => {
-    if (this.min === undefined) {
+    const { min, todayParts } = this;
+    if (min === undefined) {
       this.minParts = undefined;
       return;
     }
 
-    const { month, day, year, hour, minute } = parseDate(this.min);
-
-    this.minParts = {
-      month,
-      day,
-      year,
-      hour,
-      minute,
-    };
+    this.minParts = parseMinParts(min, todayParts);
   };
 
   private processMaxParts = () => {
-    if (this.max === undefined) {
+    const { max, todayParts } = this;
+
+    if (max === undefined) {
       this.maxParts = undefined;
       return;
     }
 
-    const { month, day, year, hour, minute } = parseDate(this.max);
-
-    this.maxParts = {
-      month,
-      day,
-      year,
-      hour,
-      minute,
-    };
+    this.maxParts = parseMaxParts(max, todayParts);
   };
 
   private initializeCalendarListener = () => {

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

@@ -1,4 +1,4 @@
-import { clampDate, getPartsFromCalendarDay, parseAmPm } from '../utils/parse';
+import { clampDate, getPartsFromCalendarDay, parseAmPm, parseMinParts, parseMaxParts } from '../utils/parse';
 
 describe('getPartsFromCalendarDay()', () => {
   it('should extract DatetimeParts from a calendar day element', () => {
@@ -72,3 +72,89 @@ describe('parseAmPm()', () => {
     expect(parseAmPm(11)).toEqual('am');
   });
 });
+
+describe('parseMinParts()', () => {
+  it('should fill in missing information when not provided', () => {
+    const today = {
+      day: 14,
+      month: 3,
+      year: 2022,
+      minute: 4,
+      hour: 2,
+    };
+    expect(parseMinParts('2012', today)).toEqual({
+      month: 1,
+      day: 1,
+      year: 2012,
+      hour: 0,
+      minute: 0,
+    });
+  });
+  it('should default to current year when only given HH:mm', () => {
+    const today = {
+      day: 14,
+      month: 3,
+      year: 2022,
+      minute: 4,
+      hour: 2,
+    };
+    expect(parseMinParts('04:30', today)).toEqual({
+      month: 1,
+      day: 1,
+      year: 2022,
+      hour: 4,
+      minute: 30,
+    });
+  });
+});
+
+describe('parseMaxParts()', () => {
+  it('should fill in missing information when not provided', () => {
+    const today = {
+      day: 14,
+      month: 3,
+      year: 2022,
+      minute: 4,
+      hour: 2,
+    };
+    expect(parseMaxParts('2012', today)).toEqual({
+      month: 12,
+      day: 31,
+      year: 2012,
+      hour: 23,
+      minute: 59,
+    });
+  });
+  it('should default to current year when only given HH:mm', () => {
+    const today = {
+      day: 14,
+      month: 3,
+      year: 2022,
+      minute: 4,
+      hour: 2,
+    };
+    expect(parseMaxParts('04:30', today)).toEqual({
+      month: 12,
+      day: 31,
+      year: 2022,
+      hour: 4,
+      minute: 30,
+    });
+  });
+  it('should fill in correct day during a leap year', () => {
+    const today = {
+      day: 14,
+      month: 3,
+      year: 2022,
+      minute: 4,
+      hour: 2,
+    };
+    expect(parseMaxParts('2012-02', today)).toEqual({
+      month: 2,
+      day: 29,
+      year: 2012,
+      hour: 23,
+      minute: 59,
+    });
+  });
+});

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

@@ -1,6 +1,7 @@
 import type { DatetimeParts } from '../datetime-interface';
 
 import { isAfter, isBefore } from './comparison';
+import { getNumDaysInMonth } from './helpers';
 
 const ISO_8601_REGEXP =
   // eslint-disable-next-line no-useless-escape
@@ -138,3 +139,72 @@ export const clampDate = (
 export const parseAmPm = (hour: number) => {
   return hour >= 12 ? 'pm' : 'am';
 };
+
+/**
+ * Takes a max date string and creates a DatetimeParts
+ * object, filling in any missing information.
+ * For example, max="2012" would fill in the missing
+ * month, day, hour, and minute information.
+ */
+export const parseMaxParts = (max: string, todayParts: DatetimeParts): DatetimeParts => {
+  const { month, day, year, hour, minute } = parseDate(max);
+
+  /**
+   * When passing in `max` or `min`, developers
+   * can pass in any ISO-8601 string. This means
+   * that not all of the date/time fields are defined.
+   * For example, passing max="2012" is valid even though
+   * there is no month, day, hour, or minute data.
+   * However, all of this data is required when clamping the date
+   * so that the correct initial value can be selected. As a result,
+   * we need to fill in any omitted data with the min or max values.
+   */
+
+  const yearValue = year ?? todayParts.year;
+  const monthValue = month ?? 12;
+  return {
+    month: monthValue,
+    day: day ?? getNumDaysInMonth(monthValue, yearValue),
+    /**
+     * Passing in "HH:mm" is a valid ISO-8601
+     * string, so we just default to the current year
+     * in this case.
+     */
+    year: yearValue,
+    hour: hour ?? 23,
+    minute: minute ?? 59,
+  };
+};
+
+/**
+ * Takes a min date string and creates a DatetimeParts
+ * object, filling in any missing information.
+ * For example, min="2012" would fill in the missing
+ * month, day, hour, and minute information.
+ */
+export const parseMinParts = (min: string, todayParts: DatetimeParts): DatetimeParts => {
+  const { month, day, year, hour, minute } = parseDate(min);
+
+  /**
+   * When passing in `max` or `min`, developers
+   * can pass in any ISO-8601 string. This means
+   * that not all of the date/time fields are defined.
+   * For example, passing max="2012" is valid even though
+   * there is no month, day, hour, or minute data.
+   * However, all of this data is required when clamping the date
+   * so that the correct initial value can be selected. As a result,
+   * we need to fill in any omitted data with the min or max values.
+   */
+  return {
+    month: month ?? 1,
+    day: day ?? 1,
+    /**
+     * Passing in "HH:mm" is a valid ISO-8601
+     * string, so we just default to the current year
+     * in this case.
+     */
+    year: year ?? todayParts.year,
+    hour: hour ?? 0,
+    minute: minute ?? 0,
+  };
+};