feat: simplify date picker shortcuts

tests/date-time-picker.test.ts

@@ -0,0 +1,72 @@
+import { describe, expect, test } from "bun:test";
+import {
+	applyQuickDateShortcut,
+	getCalendarMonthForValue,
+} from "@/components/date-time-picker";
+
+describe("DateTimePicker quick shortcuts", () => {
+	test("Today selects today, navigates the visible month, and keeps the picker open", () => {
+		const now = new Date("2026-04-09T10:30:00Z");
+
+		const result = applyQuickDateShortcut({
+			shortcut: "Today",
+			value: "2026-06-15T14:30:00",
+			allDay: false,
+			now,
+		});
+
+		expect(result.nextValue).toBe("2026-04-09T14:30:00");
+		expect(result.nextMonth.toISOString()).toBe("2026-04-09T00:00:00.000Z");
+		expect(result.keepOpen).toBe(true);
+	});
+
+	test("Next week moves selection forward a week without dropping the existing time", () => {
+		const now = new Date("2026-04-09T10:30:00Z");
+
+		const result = applyQuickDateShortcut({
+			shortcut: "Next week",
+			value: "2026-04-01T09:45:00",
+			allDay: false,
+			now,
+		});
+
+		expect(result.nextValue).toBe("2026-04-16T09:45:00");
+		expect(result.nextMonth.toISOString()).toBe("2026-04-16T00:00:00.000Z");
+	});
+
+	test("Next month updates the selected all-day date and visible month in place", () => {
+		const now = new Date("2026-04-09T10:30:00Z");
+
+		const result = applyQuickDateShortcut({
+			shortcut: "Next month",
+			value: "2026-04-01",
+			allDay: true,
+			now,
+		});
+
+		expect(result.nextValue).toBe("2026-05-09");
+		expect(result.nextMonth.toISOString()).toBe("2026-05-09T00:00:00.000Z");
+		expect(result.keepOpen).toBe(true);
+	});
+});
+
+describe("DateTimePicker visible month", () => {
+	test("uses the selected value month when one is present", () => {
+		const fallbackDate = new Date("2026-04-09T10:30:00Z");
+
+		const visibleMonth = getCalendarMonthForValue(
+			"2026-07-18T08:15:00",
+			fallbackDate,
+		);
+
+		expect(visibleMonth.toISOString()).toBe("2026-07-18T08:15:00.000Z");
+	});
+
+	test("falls back to the current month when no value is selected yet", () => {
+		const fallbackDate = new Date("2026-04-09T10:30:00Z");
+
+		const visibleMonth = getCalendarMonthForValue("", fallbackDate);
+
+		expect(visibleMonth.toISOString()).toBe("2026-04-09T10:30:00.000Z");
+	});
+});