ShouldThrowException<T> Helper

Many unit test frameworks provide an assert wrapper for an expected exception such as the following in NUnit:

Assert.Throws<T>( code here );

Some frameworks like MS Test don’t and rely on the attributes on the test itself, rather than a specific line of code e.g.

[TestMethod]
[ExpectedException(typeof(ArgumentException))]
public void GivenConstructorWhenNameIsEmptyThenArgumentExceptionThrown()
{
  code
}

If like me you prefer the more targeted nature of the latter so you can use the following code in your unit test project:

public static void ShouldThrowException<T>(Action action) where T : Exception
{
    try
    {
        action();
    }
    catch (T)
    {
        return;
    }

    Assert.Fail("Expected exception did not occur");
}

Here is an example of its usage:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace TestHelperShouldThrowException.Tests
{
    [TestClass]
    public class PersonTests
    {
        [TestMethod]
        public void GivenConstructorWhenNameIsFiveCharactersThenPersonIsCreated()
        {
            Person person = new Person("Tommy");
            Assert.IsNotNull(person);
        }

        [TestMethod]
        [ExpectedException(typeof(ArgumentException))]
        public void GivenConstructorWhenNameIsEmptyThenArgumentExceptionThrown()
        {
            Person person = new Person("");
        }

        [TestMethod]
        public void GivenConstructoWhenNameIsEmptyThenArgumentExceptionThrownUpdated()
        {
            Helper.ShouldThrowException<ArgumentException>(() => new Person(""););
        }
    }

    class Person
    {
        public string Name { get; set; }

        public Person(string name)
        {
            if (string.IsNullOrEmpty(name))
                throw new ArgumentException("Invalid name value");

            Name = name;
        }
    }
}

Source: https://github.com/stevenh77/ShouldThrowException