fix: add gantt date test

packages/gantt/src/utils/test/date.spec.ts

@@ -0,0 +1,38 @@
+import { GanttDate } from '../date';
+
+describe('tiny-date', () => {
+    const date = new GanttDate('2020-2-2 20:20:20');
+
+    it('support getTime', () => expect(date.getTime()).toBe(date.value.getTime()));
+
+    it('support getMilliseconds', () => expect(date.getMilliseconds()).toBe(date.value.getMilliseconds()));
+
+    it('support add', () => {
+        let newGanttDate: GanttDate;
+
+        newGanttDate = date.addYears(1);
+        expect(newGanttDate.getYear()).toBe(date.getYear() + 1);
+
+        newGanttDate = date.addMonths(1);
+        expect(newGanttDate.getMonth()).toBe(date.getMonth() + 1);
+
+        newGanttDate = date.addWeeks(1);
+        expect(newGanttDate.getWeek()).toBe(date.getWeek() + 1);
+
+        newGanttDate = date.addDays(1);
+        expect(newGanttDate.getDay()).toBe(date.getDay() + 1);
+
+        newGanttDate = date.addHours(1);
+        expect(newGanttDate.getHours()).toBe(date.getHours() + 1);
+
+        newGanttDate = date.addMinutes(1);
+        expect(newGanttDate.getMinutes()).toBe(date.getMinutes() + 1);
+
+        newGanttDate = date.addSeconds(1);
+        expect(newGanttDate.getSeconds()).toBe(date.getSeconds() + 1);
+    });
+
+    it('support clone', () => {
+        expect(date.getTime()).toBe(date.clone().getTime());
+    });
+});