sky/unit/test/widget/date_picker_test.dart

import 'package:flutter/material.dart';
import 'package:test/test.dart';

import 'widget_tester.dart';

void main() {
  test('Can select a day', () {
    testWidgets((WidgetTester tester) {
      DateTime currentValue;

      Widget widget = new Block(<Widget>[
        new DatePicker(
          selectedDate: new DateTime.utc(2015, 6, 9, 7, 12),
          firstDate: new DateTime.utc(2013),
          lastDate: new DateTime.utc(2018),
          onChanged: (DateTime dateTime) {
            currentValue = dateTime;
          }
        )
      ]);

      tester.pumpWidget(widget);

      expect(currentValue, isNull);
      tester.tap(tester.findText('2015'));
      tester.pumpWidget(widget);
      tester.tap(tester.findText('2014'));
      tester.pumpWidget(widget);
      expect(currentValue, equals(new DateTime(2014, 6, 9)));
      tester.tap(tester.findText('30'));
      expect(currentValue, equals(new DateTime(2013, 1, 30)));
    });
  });
}