NgbDateAdapter for Moment.js values

ngb-momentjs-adapter.ts

import { NgbDateAdapter, NgbDateStruct } from '@ng-bootstrap/ng-bootstrap';
import { Injectable } from '@angular/core';
import * as moment from 'moment';

// Might need to polyfill depending on needed browser support...
const isInt = Number.isInteger;

@Injectable()
export class NgbMomentjsAdapter extends NgbDateAdapter<moment.Moment> {

  fromModel(date: moment.Moment): NgbDateStruct {
    if (!date || !moment.isMoment(date)) {
      return null;
    }

    return {
      year: date.year(),
      month: date.month() + 1,
      day: date.date(),
    };
  }

  toModel(date: NgbDateStruct): moment.Moment {
    if (!date || !isInt(date.day) || !isInt(date.day) || !isInt(date.day)) {
      return null;
    }

    return moment(`${date.year}-${date.month}-${date.day}`, 'YYYY-MM-DD');
  }
}

tests.custom-matchers.d.ts

declare namespace jasmine {
  interface Matchers<T> {
    toBeSameMoment(expected: any, expectationFailOutput?: any): boolean;
  }
}

tests.ngb-momentjs-adapter.spec.ts

import { NgbMomentjsAdapter } from "./ngb-momentjs-adapter";
import * as moment from 'moment';

const customMatchers = {
  toBeSameMoment: (util, customEqualityTestsers) => {
    return {
      compare: (actual: moment.Moment, expected: moment.Moment) => {
        const pass = !!expected && moment.isMoment(expected)
          ? expected.isSame(actual)
          : expected === actual;

        return {
          pass: pass,
          message: pass ? '' : `Expected ${actual ? actual.toISOString() : actual} to be equal to ${expected ? expected.toISOString() : expected}.`,
        };
      }
    }
  }
};

describe('NgbMomentjsAdapter', () => {
  const adapter = new NgbMomentjsAdapter();

  beforeEach(() => {
    jasmine.addMatchers(customMatchers);
  });

  it('should roundtrip correctly', () => {
    const scenarios = [
      null,
      moment('2016-01-01', 'YYYY-MM-DD'),
      moment('2016-02-28', 'YYYY-MM-DD'),
      moment('2016-02-29', 'YYYY-MM-DD'),
      moment('2016-11-11', 'YYYY-MM-DD'),
      moment('2016-06-25', 'YYYY-MM-DD'),
      moment('2016-12-31', 'YYYY-MM-DD'),
    ];

    scenarios.forEach(input => {
      const ngbDate = adapter.fromModel(input);
      const result = adapter.toModel(ngbDate);
      expect(result).toBeSameMoment(input);
    });
  });
});

if (!date || !isInt(date.day) || !isInt(date.day) || !isInt(date.day)) {
  return null;
}

should be

if (!date || !isInt(date.year) || !isInt(date.month) || !isInt(date.day)) {
  return null;
}