Add functional test

test/LocalizationWebsite/StartupBuilderAPIs.cs

@@ -0,0 +1,42 @@
+// 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 LocalizationWebsite.Models;
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Localization;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Localization;
+using Microsoft.Extensions.Logging;
+
+namespace LocalizationWebsite
+{
+    public class StartupBuilderAPIs
+    {
+        public void ConfigureServices(IServiceCollection services)
+        {
+            services.AddLocalization(options => options.ResourcesPath = "Resources");
+        }
+
+        public void Configure(
+            IApplicationBuilder app,
+            ILoggerFactory loggerFactory,
+            IStringLocalizer<Customer> customerStringLocalizer)
+        {
+            var supportedCultures = new[] { "en-US", "fr-FR" };
+            app.UseRequestLocalization(options =>
+                options
+                    .AddSupportedCultures(supportedCultures)
+                    .AddSupportedUICultures(supportedCultures)
+                    .SetDefaultCulture("ar-YE")
+            );
+
+            app.Run(async (context) =>
+            {
+                var requestCultureFeature = context.Features.Get<IRequestCultureFeature>();
+                var requestCulture = requestCultureFeature.RequestCulture;
+                await context.Response.WriteAsync(customerStringLocalizer["Hello"]);
+            });
+        }
+    }
+}

test/Microsoft.AspNetCore.Localization.FunctionalTests/LocalizationTest.cs

@@ -77,6 +77,15 @@ namespace Microsoft.AspNetCore.Localization.FunctionalTests
                 "Bonjour from StartupResourcesAtRootFolder Bonjour from Test in root folder Bonjour from Customer in Models folder");
         }
 
+        [Fact]
+        public Task Localization_BuilderAPIs()
+        {
+            return RunTest(
+                typeof(StartupBuilderAPIs),
+                "ar-YE",
+                "Hello");
+        }
+
         private async Task RunTest(Type startupType, string culture, string expected)
         {
             var webHostBuilder = new WebHostBuilder().UseStartup(startupType);