Usability improvements:

- Remove the defaultRequestCulture parameter from IApplicationBuilder.UseRequestLocalization and make it a property on RequestLocalizationOptions instead
- Have just a single overload for IApplicationBuilder.UseRequestLocalization that takes the options
- #164

samples/LocalizationSample/Startup.cs

@@ -24,6 +24,8 @@ namespace LocalizationSample
         {
             var options = new RequestLocalizationOptions
             {
+                DefaultRequestCulture = new RequestCulture("en-US"),
+
                 // Set options here to change middleware behavior
                 SupportedCultures = new List<CultureInfo>
                 {
@@ -58,7 +60,7 @@ namespace LocalizationSample
                 
             //}));
 
-            app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+            app.UseRequestLocalization(options);
 
             app.Use(async (context, next) =>
             {

src/Microsoft.AspNet.Localization/ApplicationBuilderExtensions.cs

@@ -12,46 +12,16 @@ namespace Microsoft.AspNet.Builder
     /// </summary>
     public static class ApplicationBuilderExtensions
     {
-        /// <summary>
-        /// Adds the <see cref="RequestLocalizationMiddleware"/> to automatically set culture information for
-        /// requests based on information provided by the client using the default options.
-        /// </summary>
-        /// <param name="app">The <see cref="IApplicationBuilder"/>.</param>
-        /// <param name="defaultRequestCulture">The default <see cref="RequestCulture"/> to use if none of the
-        /// requested cultures match supported cultures.</param>
-        /// <returns>The <see cref="IApplicationBuilder"/>.</returns>
-        public static IApplicationBuilder UseRequestLocalization(
-            this IApplicationBuilder app,
-            RequestCulture defaultRequestCulture)
-        {
-            if (app == null)
-            {
-                throw new ArgumentNullException(nameof(app));
-            }
-
-            if (defaultRequestCulture == null)
-            {
-                throw new ArgumentNullException(nameof(defaultRequestCulture));
-            }
-
-            var options = new RequestLocalizationOptions();
-
-            return UseRequestLocalization(app, options, defaultRequestCulture);
-        }
-
         /// <summary>
         /// Adds the <see cref="RequestLocalizationMiddleware"/> to automatically set culture information for
         /// requests based on information provided by the client.
         /// </summary>
         /// <param name="app">The <see cref="IApplicationBuilder"/>.</param>
         /// <param name="options">The options to configure the middleware with.</param>
-        /// <param name="defaultRequestCulture">The default <see cref="RequestCulture"/> to use if none of the
-        /// requested cultures match supported cultures.</param>
         /// <returns>The <see cref="IApplicationBuilder"/>.</returns>
         public static IApplicationBuilder UseRequestLocalization(
             this IApplicationBuilder app,
-            RequestLocalizationOptions options,
+            RequestLocalizationOptions options)
-            RequestCulture defaultRequestCulture)
         {
             if (app == null)
             {
@@ -63,12 +33,7 @@ namespace Microsoft.AspNet.Builder
                 throw new ArgumentNullException(nameof(options));
             }
 
-            if (defaultRequestCulture == null)
+            return app.UseMiddleware<RequestLocalizationMiddleware>(options);
-            {
-                throw new ArgumentNullException(nameof(defaultRequestCulture));
-            }
-
-            return app.UseMiddleware<RequestLocalizationMiddleware>(options, defaultRequestCulture);
         }
     }
 }

src/Microsoft.AspNet.Localization/RequestLocalizationMiddleware.cs

@@ -6,7 +6,6 @@ using System.Collections.Generic;
 using System.Globalization;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.AspNet.Builder;
 using Microsoft.AspNet.Http;
 using Microsoft.AspNet.Http.Features;
 using Microsoft.Extensions.Globalization;
@@ -21,7 +20,6 @@ namespace Microsoft.AspNet.Localization
     {
         private readonly RequestDelegate _next;
         private readonly RequestLocalizationOptions _options;
-        private readonly RequestCulture _defaultRequestCulture;
 
         /// <summary>
         /// Creates a new <see cref="RequestLocalizationMiddleware"/>.
@@ -29,12 +27,9 @@ namespace Microsoft.AspNet.Localization
         /// <param name="next">The <see cref="RequestDelegate"/> representing the next middleware in the pipeline.</param>
         /// <param name="options">The <see cref="RequestLocalizationOptions"/> representing the options for the
         /// <see cref="RequestLocalizationMiddleware"/>.</param>
-        /// <param name="defaultRequestCulture">The default <see cref="RequestCulture"/> to use if none of the
-        /// requested cultures match supported cultures.</param>
         public RequestLocalizationMiddleware(
             RequestDelegate next,
-            RequestLocalizationOptions options,
+            RequestLocalizationOptions options)
-            RequestCulture defaultRequestCulture)
         {
             if (next == null)
             {
@@ -46,14 +41,8 @@ namespace Microsoft.AspNet.Localization
                 throw new ArgumentNullException(nameof(options));
             }
 
-            if (defaultRequestCulture == null)
-            {
-                throw new ArgumentNullException(nameof(defaultRequestCulture));
-            }
-
             _next = next;
             _options = options;
-            _defaultRequestCulture = defaultRequestCulture;
         }
 
         /// <summary>
@@ -68,7 +57,7 @@ namespace Microsoft.AspNet.Localization
                 throw new ArgumentNullException(nameof(context));
             }
 
-            var requestCulture = _defaultRequestCulture;
+            var requestCulture = _options.DefaultRequestCulture;
 
             IRequestCultureProvider winningProvider = null;
 
@@ -100,11 +89,11 @@ namespace Microsoft.AspNet.Localization
                         }
                         if (cultureInfo == null && uiCultureInfo != null)
                         {
-                            cultureInfo = _defaultRequestCulture.Culture;
+                            cultureInfo = _options.DefaultRequestCulture.Culture;
                         }
                         if (cultureInfo != null && uiCultureInfo == null)
                         {
-                            uiCultureInfo = _defaultRequestCulture.UICulture;
+                            uiCultureInfo = _options.DefaultRequestCulture.UICulture;
                         }
 
                         var result = new RequestCulture(cultureInfo, uiCultureInfo);

src/Microsoft.AspNet.Localization/RequestLocalizationOptions.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Globalization;
 
@@ -11,6 +12,9 @@ namespace Microsoft.AspNet.Localization
     /// </summary>
     public class RequestLocalizationOptions
     {
+        private RequestCulture _defaultRequestCulture =
+            new RequestCulture(CultureInfo.CurrentCulture, CultureInfo.CurrentUICulture);
+
         /// <summary>
         /// Creates a new <see cref="RequestLocalizationOptions"/> with default values.
         /// </summary>
@@ -25,20 +29,40 @@ namespace Microsoft.AspNet.Localization
         }
 
         /// <summary>
-        /// The cultures supported by the application. If this value is non-<c>null</c>, the
+        /// Gets or sets the default culture to use for requests when a supported culture could not be determined by
-        /// <see cref="RequestLocalizationMiddleware"/> will only set the current request culture to an entry in this
+        /// one of the configured <see cref="IRequestCultureProvider"/>s.
-        /// list. A value of <c>null</c> means all cultures are supported.
+        /// Defaults to <see cref="CultureInfo.CurrentCulture"/> and <see cref="CultureInfo.CurrentUICulture"/>.
-        /// Defaults to <c>null</c>.
         /// </summary>
-        public IList<CultureInfo> SupportedCultures { get; set; }
+        public RequestCulture DefaultRequestCulture
+        {
+            get
+            {
+                return _defaultRequestCulture;
+            }
+            set
+            {
+                if (value == null)
+                {
+                    throw new ArgumentNullException(nameof(value));
+                }
+
+                _defaultRequestCulture = value;
+            }
+        }
 
         /// <summary>
-        /// The UI cultures supported by the application. If this value is non-<c>null</c>, the
+        /// The cultures supported by the application. The <see cref="RequestLocalizationMiddleware"/> will only set
-        /// <see cref="RequestLocalizationMiddleware"/> will only set the current request culture to an entry in this
+        /// the current request culture to an entry in this list.
-        /// list. A value of <c>null</c> means all cultures are supported.
+        /// Defaults to <see cref="CultureInfo.CurrentCulture"/>.
-        /// Defaults to <c>null</c>.
         /// </summary>
-        public IList<CultureInfo> SupportedUICultures { get; set; }
+        public IList<CultureInfo> SupportedCultures { get; set; } = new List<CultureInfo> { CultureInfo.CurrentCulture };
+
+        /// <summary>
+        /// The UI cultures supported by the application. The <see cref="RequestLocalizationMiddleware"/> will only set
+        /// the current request culture to an entry in this list.
+        /// Defaults to <see cref="CultureInfo.CurrentUICulture"/>.
+        /// </summary>
+        public IList<CultureInfo> SupportedUICultures { get; set; } = new List<CultureInfo> { CultureInfo.CurrentUICulture };
 
         /// <summary>
         /// An ordered list of providers used to determine a request's culture information. The first provider that

test/LocalizationWebsite/StartupResourcesAtRootFolder.cs

@@ -31,6 +31,7 @@ namespace LocalizationWebsite
 
             var options = new RequestLocalizationOptions
             {
+                DefaultRequestCulture = new RequestCulture("en-US"),
                 SupportedCultures = new List<CultureInfo>()
                 {
                     new CultureInfo("fr-FR")
@@ -41,7 +42,7 @@ namespace LocalizationWebsite
                 }
             };
 
-            app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+            app.UseRequestLocalization(options);
 
             var stringLocalizer = stringLocalizerFactory.Create("Test", location: null);
 

test/LocalizationWebsite/StartupResourcesInFolder.cs

@@ -31,6 +31,7 @@ namespace LocalizationWebsite
 
             var options = new RequestLocalizationOptions
             {
+                DefaultRequestCulture = new RequestCulture("en-US"),
                 SupportedCultures = new List<CultureInfo>()
                 {
                     new CultureInfo("fr-FR")
@@ -41,7 +42,7 @@ namespace LocalizationWebsite
                 }
             };
 
-            app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+            app.UseRequestLocalization(options);
 
             var stringLocalizer = stringLocalizerFactory.Create("Test", location: null);
 

test/Microsoft.AspNet.Localization.Tests/AcceptLanguageHeaderRequestCultureProviderTest.cs

@@ -21,13 +21,14 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA"),
                         new CultureInfo("en-US")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -52,13 +53,14 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions
                 {
+                    DefaultRequestCulture = new RequestCulture("fr-FR"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA"),
                         new CultureInfo("en-US")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("fr-FR"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -82,13 +84,14 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions
                 {
+                    DefaultRequestCulture = new RequestCulture("fr-FR"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA"),
                         new CultureInfo("af-ZA")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("fr-FR"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -113,6 +116,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-YE")
@@ -122,7 +126,7 @@ namespace Microsoft.Extensions.Localization.Tests
                         new CultureInfo("ar-YE")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();

test/Microsoft.AspNet.Localization.Tests/CookieRequestCultureProviderTest.cs

@@ -22,6 +22,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -34,7 +35,7 @@ namespace Microsoft.Extensions.Localization.Tests
                 var provider = new CookieRequestCultureProvider();
                 provider.CookieName = "Preferences";
                 options.RequestCultureProviders.Insert(0, provider);
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -61,6 +62,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -73,7 +75,7 @@ namespace Microsoft.Extensions.Localization.Tests
                 var provider = new CookieRequestCultureProvider();
                 provider.CookieName = "Preferences";
                 options.RequestCultureProviders.Insert(0, provider);
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -96,6 +98,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -108,7 +111,7 @@ namespace Microsoft.Extensions.Localization.Tests
                 var provider = new CookieRequestCultureProvider();
                 provider.CookieName = "Preferences";
                 options.RequestCultureProviders.Insert(0, provider);
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();

test/Microsoft.AspNet.Localization.Tests/CustomRequestCultureProviderTest.cs

@@ -24,6 +24,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar")
@@ -39,7 +40,7 @@ namespace Microsoft.Extensions.Localization.Tests
                     var requestCulture = new ProviderCultureResult(culture);
                     return Task.FromResult(requestCulture);
                 }));
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();

test/Microsoft.AspNet.Localization.Tests/QueryStringRequestCultureProviderTest.cs

@@ -21,6 +21,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -31,7 +32,7 @@ namespace Microsoft.Extensions.Localization.Tests
                     }
                 };
 
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -52,8 +53,11 @@ namespace Microsoft.Extensions.Localization.Tests
         {
             using (var server = TestServer.Create(app =>
             {
-                var options = new RequestLocalizationOptions();
+                var options = new RequestLocalizationOptions
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
+                };
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -76,6 +80,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -85,7 +90,7 @@ namespace Microsoft.Extensions.Localization.Tests
                         new CultureInfo("ar-SA")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -107,6 +112,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -116,7 +122,7 @@ namespace Microsoft.Extensions.Localization.Tests
                         new CultureInfo("ar-SA")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -138,6 +144,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -147,7 +154,7 @@ namespace Microsoft.Extensions.Localization.Tests
                         new CultureInfo("ar-SA")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -170,6 +177,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -179,7 +187,7 @@ namespace Microsoft.Extensions.Localization.Tests
                         new CultureInfo("ar-SA")
                     }
                 };
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -202,6 +210,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("ar-SA")
@@ -215,7 +224,7 @@ namespace Microsoft.Extensions.Localization.Tests
                 provider.QueryStringKey = "c";
                 provider.UIQueryStringKey = "uic";
                 options.RequestCultureProviders.Insert(0, provider);
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
@@ -238,6 +247,7 @@ namespace Microsoft.Extensions.Localization.Tests
             {
                 var options = new RequestLocalizationOptions()
                 {
+                    DefaultRequestCulture = new RequestCulture("en-US"),
                     SupportedCultures = new List<CultureInfo>
                     {
                         new CultureInfo("FR")
@@ -251,7 +261,7 @@ namespace Microsoft.Extensions.Localization.Tests
                 provider.QueryStringKey = "c";
                 provider.UIQueryStringKey = "uic";
                 options.RequestCultureProviders.Insert(0, provider);
-                app.UseRequestLocalization(options, defaultRequestCulture: new RequestCulture("en-US"));
+                app.UseRequestLocalization(options);
                 app.Run(context =>
                 {
                     var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();

test/Microsoft.AspNet.Localization.Tests/RequestLocalizationOptionsTest.cs

@@ -0,0 +1,107 @@
+// Copyright (c) .NET Foundation. All rights reserved. 
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Globalization;
+using System.Threading;
+using Xunit;
+
+namespace Microsoft.AspNet.Localization.Tests
+{
+    public class RequestLocalizationOptionsTest : IDisposable
+    {
+        private readonly CultureInfo _initialCulture;
+        private readonly CultureInfo _initialUICulture;
+
+        public RequestLocalizationOptionsTest()
+        {
+            _initialCulture = CultureInfo.CurrentCulture;
+            _initialUICulture = CultureInfo.CurrentUICulture;
+        }
+
+        [Fact]
+        public void DefaultRequestCulture_DefaultsToCurrentCulture()
+        {
+            // Arrange/Act
+            var options = new RequestLocalizationOptions();
+
+            // Assert
+            Assert.NotNull(options.DefaultRequestCulture);
+            Assert.Equal(CultureInfo.CurrentCulture, options.DefaultRequestCulture.Culture);
+            Assert.Equal(CultureInfo.CurrentUICulture, options.DefaultRequestCulture.UICulture);
+        }
+
+        [Fact]
+        public void DefaultRequestCulture_DefaultsToCurrentCultureWhenExplicitlySet()
+        {
+            // Arrange
+            var explicitCulture = new CultureInfo("fr-FR");
+#if DNX451
+            Thread.CurrentThread.CurrentCulture = explicitCulture;
+            Thread.CurrentThread.CurrentUICulture = explicitCulture;
+#else
+            CultureInfo.CurrentCulture = explicitCulture;
+            CultureInfo.CurrentUICulture = explicitCulture;
+#endif
+            // Act
+            var options = new RequestLocalizationOptions();
+
+            // Assert
+            Assert.Equal(explicitCulture, options.DefaultRequestCulture.Culture);
+            Assert.Equal(explicitCulture, options.DefaultRequestCulture.UICulture);
+        }
+
+        [Fact]
+        public void DefaultRequestCulture_ThrowsWhenTryingToSetToNull()
+        {
+            // Arrange
+            var options = new RequestLocalizationOptions();
+
+            // Act/Assert
+            Assert.Throws(typeof(ArgumentNullException), () => options.DefaultRequestCulture = null);
+        }
+
+        [Fact]
+        public void SupportedCultures_DefaultsToCurrentCulture()
+        {
+            // Arrange/Act
+            var options = new RequestLocalizationOptions();
+
+            // Assert
+            Assert.Collection(options.SupportedCultures, item => Assert.Equal(CultureInfo.CurrentCulture, item));
+            Assert.Collection(options.SupportedUICultures, item => Assert.Equal(CultureInfo.CurrentUICulture, item));
+        }
+
+        [Fact]
+        public void SupportedCultures_DefaultsToCurrentCultureWhenExplicitlySet()
+        {
+            // Arrange
+            var explicitCulture = new CultureInfo("fr-FR");
+#if DNX451
+            Thread.CurrentThread.CurrentCulture = explicitCulture;
+            Thread.CurrentThread.CurrentUICulture = explicitCulture;
+#else
+            CultureInfo.CurrentCulture = explicitCulture;
+            CultureInfo.CurrentUICulture = explicitCulture;
+#endif
+
+            // Act
+            var options = new RequestLocalizationOptions();
+
+            // Assert
+            Assert.Collection(options.SupportedCultures, item => Assert.Equal(explicitCulture, item));
+            Assert.Collection(options.SupportedUICultures, item => Assert.Equal(explicitCulture, item));
+        }
+
+        public void Dispose()
+        {
+#if DNX451
+            Thread.CurrentThread.CurrentCulture = _initialCulture;
+            Thread.CurrentThread.CurrentUICulture = _initialUICulture;
+#else
+            CultureInfo.CurrentCulture = _initialCulture;
+            CultureInfo.CurrentUICulture = _initialUICulture;
+#endif
+        }
+    }
+}