fix(datepicker): fix error when selecting month with fewer days in year (#6129)

view

src/lib/datepicker/year-view.spec.ts

@@ -1,10 +1,10 @@
 import {async, ComponentFixture, TestBed} from '@angular/core/testing';
-import {Component} from '@angular/core';
+import {Component, ViewChild} from '@angular/core';
 import {By} from '@angular/platform-browser';
 import {MdYearView} from './year-view';
 import {MdCalendarBody} from './calendar-body';
 import {MdNativeDateModule} from '../core/datetime/index';
-import {FEB, JAN, MAR} from '../core/testing/month-constants';
+import {FEB, JAN, JUL, JUN, MAR} from '../core/testing/month-constants';
 
 describe('MdYearView', () => {
   beforeEach(async(() => {
@@ -76,6 +76,16 @@ describe('MdYearView', () => {
       expect((cellEls[0] as HTMLElement).innerText.trim()).toBe('JAN');
       expect(cellEls[0].classList).toContain('mat-calendar-body-active');
     });
+
+    it('should allow selection of month with less days than current active date', () => {
+      testComponent.date = new Date(2017, JUL, 31);
+      fixture.detectChanges();
+
+      expect(testComponent.yearView._monthSelected(JUN));
+      fixture.detectChanges();
+
+      expect(testComponent.selected).toEqual(new Date(2017, JUN, 30));
+    });
   });
 
   describe('year view with date filter', () => {
@@ -108,6 +118,8 @@ describe('MdYearView', () => {
 class StandardYearView {
   date = new Date(2017, JAN, 5);
   selected = new Date(2017, MAR, 10);
+
+  @ViewChild(MdYearView) yearView: MdYearView<Date>;
 }
 
 

src/lib/datepicker/year-view.ts

@@ -95,9 +95,11 @@ export class MdYearView<D> implements AfterContentInit {
 
   /** Handles when a new month is selected. */
   _monthSelected(month: number) {
+    let daysInMonth = this._dateAdapter.getNumDaysInMonth(
+        this._dateAdapter.createDate(this._dateAdapter.getYear(this.activeDate), month, 1));
     this.selectedChange.emit(this._dateAdapter.createDate(
         this._dateAdapter.getYear(this.activeDate), month,
-        this._dateAdapter.getDate(this.activeDate)));
+        Math.min(this._dateAdapter.getDate(this.activeDate), daysInMonth)));
   }
 
   /** Initializes this month view. */