XUnit - Change culture during your test execution

Most of the applications I’m building should support multiple languages and cultures. This means that I also need to test my application code taking into account this into account.

In XUnit, there is no out-of-the-box way to change the culture of your unit test. However XUnit is easy to extend and you can even find a UseCultureAttribute example that exacty provides the functionality I need.

	using System;
	using System.Globalization;
	using System.Linq;
	using System.Reflection;
	using System.Threading;
	using Xunit.Sdk;
	/// <summary>
	/// Apply this attribute to your test method to replace the
	/// <see cref="Thread.CurrentThread" /> <see cref="CultureInfo.CurrentCulture" /> and
	/// <see cref="CultureInfo.CurrentUICulture" /> with another culture.
	/// </summary>
	[AttributeUsage(AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)]
	public class UseCultureAttribute : BeforeAfterTestAttribute
	{
	readonly Lazy<CultureInfo> culture;
	readonly Lazy<CultureInfo> uiCulture;
	CultureInfo originalCulture;
	CultureInfo originalUICulture;
	/// <summary>
	/// Replaces the culture and UI culture of the current thread with
	/// <paramref name="culture" />
	/// </summary>
	/// <param name="culture">The name of the culture.</param>
	/// <remarks>
	/// <para>
	/// This constructor overload uses <paramref name="culture" /> for both
	/// <see cref="Culture" /> and <see cref="UICulture" />.
	/// </para>
	/// </remarks>
	public UseCultureAttribute(string culture)
	: this(culture, culture) { }
	/// <summary>
	/// Replaces the culture and UI culture of the current thread with
	/// <paramref name="culture" /> and <paramref name="uiCulture" />
	/// </summary>
	/// <param name="culture">The name of the culture.</param>
	/// <param name="uiCulture">The name of the UI culture.</param>
	public UseCultureAttribute(string culture, string uiCulture)
	{
	this.culture = new Lazy<CultureInfo>(() => new CultureInfo(culture, false));
	this.uiCulture = new Lazy<CultureInfo>(() => new CultureInfo(uiCulture, false));
	}
	/// <summary>
	/// Gets the culture.
	/// </summary>
	public CultureInfo Culture { get { return culture.Value; } }
	/// <summary>
	/// Gets the UI culture.
	/// </summary>
	public CultureInfo UICulture { get { return uiCulture.Value; } }
	/// <summary>
	/// Stores the current <see cref="Thread.CurrentPrincipal" />
	/// <see cref="CultureInfo.CurrentCulture" /> and <see cref="CultureInfo.CurrentUICulture" />
	/// and replaces them with the new cultures defined in the constructor.
	/// </summary>
	/// <param name="methodUnderTest">The method under test</param>
	public override void Before(MethodInfo methodUnderTest)
	{
	originalCulture = Thread.CurrentThread.CurrentCulture;
	originalUICulture = Thread.CurrentThread.CurrentUICulture;
	Thread.CurrentThread.CurrentCulture = Culture;
	Thread.CurrentThread.CurrentUICulture = UICulture;
	CultureInfo.CurrentCulture.ClearCachedData();
	CultureInfo.CurrentUICulture.ClearCachedData();
	}
	/// <summary>
	/// Restores the original <see cref="CultureInfo.CurrentCulture" /> and
	/// <see cref="CultureInfo.CurrentUICulture" /> to <see cref="Thread.CurrentPrincipal" />
	/// </summary>
	/// <param name="methodUnderTest">The method under test</param>
	public override void After(MethodInfo methodUnderTest)
	{
	Thread.CurrentThread.CurrentCulture = originalCulture;
	Thread.CurrentThread.CurrentUICulture = originalUICulture;
	CultureInfo.CurrentCulture.ClearCachedData();
	CultureInfo.CurrentUICulture.ClearCachedData();
	}
	}

view raw UseCultureAttribute.cs hosted with ❤ by GitHub

Here is an example where I used this attribute to test if my validation messages are translated correctly:

	[UseCulture("nl-BE")]
	[Fact]
	public void Validator_TranslatesValidationMessages_Based_On_CurrentUICulture()
	{
	//Arrange
	var invalidOrder = new Order();
	invalidOrder.Orderlines.Add(new Orderline());
	//Act
	var validator = _fixture.Container.Resolve<IValidator>();
	var result = validator.Validate(invalidOrder);
	//Assert
	Assert.False(result.IsValid);
	Assert.Equal(5, result.ValidationErrors.Count);
	Assert.Equal("'Id' mag niet leeg zijn.", result.ValidationErrors[0].ToString());
	Assert.Equal("'Name' mag niet leeg zijn.", result.ValidationErrors[1].ToString());
	Assert.Equal("'Email Address' mag niet leeg zijn.", result.ValidationErrors[2].ToString());
	Assert.Equal("'Product' mag niet leeg zijn.", result.ValidationErrors[3].ToString());
	Assert.Equal("'Amount' moet groter zijn dan of gelijk zijn aan '1'.", result.ValidationErrors[4].ToString());
	}

view raw UseCultureTest.cs hosted with ❤ by GitHub