using System;
using NUnit.Framework;

namespace Chernobyl
{
    // ReSharper disable ObjectCreationAsStatement

    [TestFixture, Description("Tests for the ActionCombiner<T1, T2> type.")]
    public class ActionCombinerT1T2Tests
    {
        [Test, Description("Ensures the constructor throws an ArgumentNullException " +
            "when it is passed a null argument")]
        public void ConstructorArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(() => new ActionCombiner<int, int>(null));
        }

        [Test, Description("Ensures the main action method passed to the " +
            "ActionCombiner<T1, T2> is invoked at the proper time with the " +
            "correct arguments.")]
        public void ActionInvokedWithProperArguments()
        {
            Tester tester = new Tester();
            ActionCombiner<int, int> actionCombiner =
                new ActionCombiner<int, int>(tester.Action);

            actionCombiner.Second(2);
            tester.MainActionInvocationImminent = true;
            actionCombiner.First(1);
        }

        /// <summary>
        /// A utility type used to help test <see cref="ActionCombiner{T1, T2}"/>.
        /// </summary>
        class Tester
        {
            public bool MainActionInvocationImminent;

            public void Action(int x, int y)
            {
                Assert.True(MainActionInvocationImminent, "The main action method " +
                    "was invoked at the incorrect time.");
                Assert.AreEqual(1, x, "First argument is not correct.");
                Assert.AreEqual(2, y, "Second argument is not correct.");
            }
        }
    }

    [TestFixture, Description("Tests for the ActionCombiner<T1, T2, T3> type.")]
    public class ActionCombinerT1T2T3Tests
    {
        [Test, Description("Ensures the constructor throws an ArgumentNullException " +
            "when it is passed a null argument")]
        public void ConstructorArgumentNullException()
        {
            Assert.Throws<ArgumentNullException>(() => new ActionCombiner<int, int, int>(null));
        }

        [Test, Description("Ensures the main action method passed to the " +
            "ActionCombiner<T1, T2, T3> is invoked at the proper time with the " +
            "correct arguments.")]
        public void ActionInvokedWithProperArguments()
        {
            Tester tester = new Tester();
            ActionCombiner<int, int, int> actionCombiner =
                new ActionCombiner<int, int, int>(tester.Action);

            actionCombiner.Third(3);
            actionCombiner.First(1);
            tester.MainActionInvocationImminent = true;
            actionCombiner.Second(2);
        }

        /// <summary>
        /// A utility type used to help test <see cref="ActionCombiner{T1, T2, T3}"/>.
        /// </summary>
        class Tester
        {
            public bool MainActionInvocationImminent;

            public void Action(int x, int y, int z)
            {
                Assert.True(MainActionInvocationImminent, "The main action method " +
                    "was invoked at the incorrect time.");
                Assert.AreEqual(1, x, "First argument is not correct.");
                Assert.AreEqual(2, y, "Second argument is not correct.");
                Assert.AreEqual(3, z, "Third argument is not correct.");
            }
        }
    }

    // ReSharper restore ObjectCreationAsStatement
}