/SolarSystem.Tests/PlanetarySystemTests.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Threading.Tasks;

using Moq;

using NUnit.Framework;



namespace SolarSystem.Tests

{

    [TestFixture]

    public class PlanetarySystemTests

    {

        [Test]

        public void Constructor()

        {

            var mockPlanetOne = new Mock<IPlanet>();

            var mockPlanetTwo = new Mock<IPlanet>();



            var planets = new[] { mockPlanetOne.Object, mockPlanetTwo.Object };

            var system = new PlanetarySystem(planets);



            Assert.That(system.Planets.Contains(mockPlanetOne.Object));

            Assert.That(system.Planets.Contains(mockPlanetTwo.Object));

            Assert.That(system.TimeElapsed, Is.EqualTo(TimeSpan.Zero));

        }



        [Test]

        public void TickCallsTickOnAllPlanets()

        {

            var mockPlanetOne = new Mock<IPlanet>();

            var mockPlanetTwo = new Mock<IPlanet>();



            var planets = new[] { mockPlanetOne.Object, mockPlanetTwo.Object };

            var system = new PlanetarySystem(planets);



            system.ElapseDays(5);



            mockPlanetOne.Verify(v => v.ElapseDays(5), Times.Once());

            mockPlanetTwo.Verify(v => v.ElapseDays(5), Times.Once());

        }



        [Test]

        public void TickIncreasesTimeElapsed()

        {

            var system = new PlanetarySystem(Enumerable.Empty<IPlanet>());

            system.ElapseDays(5);

            Assert.That(system.TimeElapsed, Is.EqualTo(TimeSpan.FromDays(5)));

        }

    }

}