Add extension method for getting environment name

Fixes: #100

src/Microsoft.AspNet.Hosting.Interfaces/HostingEnvironmentExtensions.cs

@@ -0,0 +1,27 @@
+// Copyright (c) Microsoft Open Technologies, Inc. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.Framework.Internal;
+
+namespace Microsoft.AspNet.Hosting
+{
+    public static class HostingEnvironmentExtensions
+    {
+        /// <summary>
+        /// Compares the current hosting environment name against the specified value.
+        /// </summary>
+        /// <param name="hostingEnvironment">An instance of <see cref="IHostingEnvironment"/> service.</param>
+        /// <param name="environmentName">Environment name to validate against.</param>
+        /// <returns>True if the specified name is same as the current environment.</returns>
+        public static bool IsEnvironment(
+            [NotNull]this IHostingEnvironment hostingEnvironment,
+            [NotNull]string environmentName)
+        {
+            return string.Equals(
+                hostingEnvironment.EnvironmentName,
+                environmentName,
+                StringComparison.OrdinalIgnoreCase);
+        }
+    }
+}

src/Microsoft.AspNet.Hosting.Interfaces/project.json

@@ -4,10 +4,11 @@
         "Microsoft.AspNet.Http": "1.0.0-*",
         "Microsoft.AspNet.FeatureModel": "1.0.0-*",
         "Microsoft.AspNet.FileProviders.Interfaces": "1.0.0-*",
-        "Microsoft.Framework.ConfigurationModel": "1.0.0-*"
+        "Microsoft.Framework.ConfigurationModel": "1.0.0-*",
+        "Microsoft.Framework.NotNullAttribute.Internal": { "type": "build", "version": "1.0.0-*" }
     },
     "frameworks": {
         "dnx451": {},
         "dnxcore50": {}
     }
-}
+}

test/Microsoft.AspNet.Hosting.Tests/HostingEngineTests.cs

@@ -63,6 +63,32 @@ public void WebRootCanBeResolvedFromTheProjectJson()
             Assert.True(env.WebRootFileProvider.GetFileInfo("TextFile.txt").Exists);
         }
 
+        [Fact]
+        public void Validate_Environment_Name()
+        {
+            var services = HostingServices.Create().BuildServiceProvider();
+            var env = services.GetRequiredService<IHostingEnvironment>();
+            Assert.Equal("Development", env.EnvironmentName);
+
+            var config = new Configuration()
+                .AddCommandLine(new string[] { "--ASPNET_ENV", "Overridden_Environment" });
+
+            services = HostingServices.Create(fallbackServices: null, configuration: config)
+                .BuildServiceProvider();
+
+            env = services.GetRequiredService<IHostingEnvironment>();
+            Assert.Equal("Overridden_Environment", env.EnvironmentName);
+        }
+
+        [Fact]
+        public void IsEnvironment_Extension_Is_Case_Insensitive()
+        {
+            var services = HostingServices.Create().BuildServiceProvider();
+            var env = services.GetRequiredService<IHostingEnvironment>();
+            Assert.True(env.IsEnvironment("Development"));
+            Assert.True(env.IsEnvironment("developMent"));
+        }
+
         public void Initialize(IApplicationBuilder builder)
         {