Awaitable Assert.Throws implementation.

AssertPlus.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

using NUnit.Framework;

namespace Samples {
    public static class AssertPlus {
        public static async Task Throws<TException>(Func<Task> inTestCallback) where TException: Exception {
            try {
                await inTestCallback();
            }
            catch (Exception ex) {
                Assert.That(ex, Is.TypeOf<TException>());
            }
        }
    }

    [TestFixture]
    public class _AssertPlusをテストするためのTestSuite {
        [Test]
        public void _TestThrows_Success() {
            try {
                AssertPlus.Throws<NotSupportedException>(async () => {
                    await Task.Factory.StartNew(() => {
                        throw new NotSupportedException();
                    });
                }).GetAwaiter().GetResult();
            }
            catch {
                Assert.Fail("The specified exception is caught.");
            }
        }

        [Test]
        public void _TestThrows_Failed_1() {
            try {
                AssertPlus.Throws<NotSupportedException>(async () => {
                    await Task.Factory.StartNew(() => {
                        throw new ArgumentException();
                    });
                }).GetAwaiter().GetResult();

                Assert.Fail("Must be failed.");
            }
            catch {
                Assert.Pass("OK");
            }
        }

        [Test]
        public void _TestThrows_Failed_2() {
            try {
                AssertPlus.Throws<NotSupportedException>(async () => {
                    await Task.Factory.StartNew(() => {
                        throw new Exception();
                    });
                }).GetAwaiter().GetResult();

                Assert.Fail("Must be failed.");
            }
            catch {
                Assert.Pass("OK");
            }
        }
    }
}

Outer GetAwaiter().GetResult() will be replaced to the await syntax using TestSyncContext at https://gist.github.com/2880770