Added the EnvironmentTagHelper:

- #1553

Mvc.NoFun.sln

@@ -44,6 +44,12 @@ Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.WebApi
 EndProject
 Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.TestConfiguration", "test\WebSites\Microsoft.AspNet.Mvc.TestConfiguration\Microsoft.AspNet.Mvc.TestConfiguration.kproj", "{680D75ED-601F-4D86-B01B-1072D0C31B8C}"
 EndProject
+Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.TagHelpers", "src\Microsoft.AspNet.Mvc.TagHelpers\Microsoft.AspNet.Mvc.TagHelpers.kproj", "{B2347320-308E-4D2B-AEC8-005DFA68B0C9}"
+EndProject
+Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "TagHelperSample.Web", "samples\TagHelperSample.Web\TagHelperSample.Web.kproj", "{2223120F-D675-40DA-8CD8-11DC14A0B2C7}"
+EndProject
+Project("{8BB2217D-0F2D-49D1-97BC-3654ED321F3B}") = "Microsoft.AspNet.Mvc.TagHelpers.Test", "test\Microsoft.AspNet.Mvc.TagHelpers.Test\Microsoft.AspNet.Mvc.TagHelpers.Test.kproj", "{860119ED-3DB1-424D-8D0A-30132A8A7D96}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -206,6 +212,42 @@ Global
 		{680D75ED-601F-4D86-B01B-1072D0C31B8C}.Release|Mixed Platforms.Build.0 = Release|Any CPU
 		{680D75ED-601F-4D86-B01B-1072D0C31B8C}.Release|x86.ActiveCfg = Release|Any CPU
 		{680D75ED-601F-4D86-B01B-1072D0C31B8C}.Release|x86.Build.0 = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Debug|x86.Build.0 = Debug|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Any CPU.Build.0 = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|x86.ActiveCfg = Release|Any CPU
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9}.Release|x86.Build.0 = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Debug|x86.Build.0 = Debug|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Any CPU.Build.0 = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|x86.ActiveCfg = Release|Any CPU
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7}.Release|x86.Build.0 = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|Mixed Platforms.ActiveCfg = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|Mixed Platforms.Build.0 = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Debug|x86.Build.0 = Debug|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|Any CPU.Build.0 = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|Mixed Platforms.ActiveCfg = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|Mixed Platforms.Build.0 = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|x86.ActiveCfg = Release|Any CPU
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -226,5 +268,8 @@ Global
 		{23D30B8C-04B1-4577-A604-ED27EA1E4A0E} = {32285FA4-6B46-4D6B-A840-2B13E4C8B58E}
 		{5DE8E4D9-AACD-4B5F-819F-F091383FB996} = {3BA657BF-28B1-42DA-B5B0-1C4601FCF7B1}
 		{680D75ED-601F-4D86-B01B-1072D0C31B8C} = {3BA657BF-28B1-42DA-B5B0-1C4601FCF7B1}
+		{B2347320-308E-4D2B-AEC8-005DFA68B0C9} = {32285FA4-6B46-4D6B-A840-2B13E4C8B58E}
+		{2223120F-D675-40DA-8CD8-11DC14A0B2C7} = {DAAE4C74-D06F-4874-A166-33305D2643CE}
+		{860119ED-3DB1-424D-8D0A-30132A8A7D96} = {3BA657BF-28B1-42DA-B5B0-1C4601FCF7B1}
 	EndGlobalSection
 EndGlobal

samples/TagHelperSample.Web/Views/Home/Index.cshtml

@@ -2,6 +2,10 @@
 @using TagHelperSample.Web.Models
 @model IList<User>
 
+<environment names="development">
+    Hello, you're in Development
+</environment>
+
 <h2>Index</h2>
 @if (Model != null && Model.Count() != 0)
 {

src/Microsoft.AspNet.Mvc.TagHelpers/EnvironmentTagHelper.cs

@@ -0,0 +1,72 @@
+// 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 System.Linq;
+using Microsoft.AspNet.Hosting;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+
+namespace Microsoft.AspNet.Mvc.TagHelpers
+{
+    /// <summary>
+    /// <see cref="ITagHelper"/> implementation targeting &lt;environment&gt; elements that conditionally renders
+    /// content based on the current value of <see cref="IHostingEnvironment.EnvironmentName"/>.
+    /// </summary>
+    public class EnvironmentTagHelper : TagHelper
+    {
+        private static readonly char[] NameSeparator = new[] { ',' };
+
+        /// <summary>
+        /// A comma separated list of environment names in which the content should be rendered.
+        /// </summary>
+        /// <remarks>
+        /// The specified environment names are compared case insensitively to the current value of
+        /// <see cref="IHostingEnvironment.EnvironmentName"/>.
+        /// </remarks>
+        public string Names { get; set; }
+
+        // Protected to ensure subclasses are correctly activated. Internal for ease of use when testing.
+        [Activate]
+        protected internal IHostingEnvironment HostingEnvironment { get; set; }
+
+        /// <inheritdoc />
+        public override void Process(TagHelperContext context, TagHelperOutput output)
+        {
+            // Always strip the outer tag name as we never want <environment> to render
+            output.TagName = null;
+
+            if (string.IsNullOrWhiteSpace(Names))
+            {
+                // No names specified, do nothing
+                return;
+            }
+
+            var environments = Names.Split(NameSeparator, StringSplitOptions.RemoveEmptyEntries)
+                                    .Where(name => !string.IsNullOrWhiteSpace(name));
+
+            if (!environments.Any())
+            {
+                // Names contains only commas or empty entries, do nothing
+                return;
+            }
+
+            var currentEnvironmentName = HostingEnvironment.EnvironmentName?.Trim();
+
+            if (string.IsNullOrWhiteSpace(currentEnvironmentName))
+            {
+                // No current environment name, do nothing
+                return;
+            }
+
+            if (environments.Any(name =>
+                string.Equals(name.Trim(), currentEnvironmentName, StringComparison.OrdinalIgnoreCase)))
+            {
+                // Matching environment name found, do nothing
+                return;
+            }
+            
+            // No matching environment name found, suppress all output
+            output.SuppressOutput();
+        }
+    }
+}

test/Microsoft.AspNet.Mvc.FunctionalTests/Compiler/Resources/MvcTagHelpersWebSite.MvcTagHelper_Home.Environment.html

@@ -0,0 +1,44 @@
+
+<!doctype html>
+<html>
+<head>
+    <meta charset="utf-8" />
+    <title>Environment</title>
+</head>
+<body>
+
+    <h2>Environment Tag Helper Test</h2>
+
+    <ul>
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+            <li>This will show</li>
+        
+        
+        
+    </ul>
+</body>
+</html>

test/Microsoft.AspNet.Mvc.FunctionalTests/MvcTagHelpersTests.cs

@@ -33,7 +33,9 @@ namespace Microsoft.AspNet.Mvc.FunctionalTests
         // Testing SelectTagHelper with Html.BeginForm 
         [InlineData("CreateWarehouse", null)] 
         // Testing the HTML helpers with FormTagHelper
-        [InlineData("EditWarehouse", null)] 
+        [InlineData("EditWarehouse", null)]
+        // Testing the EnvironmentTagHelper
+        [InlineData("Environment", null)]
         public async Task MvcTagHelpers_GeneratesExpectedResults(string action, string antiForgeryPath)
         {
             // Arrange

test/Microsoft.AspNet.Mvc.TagHelpers.Test/EnvironmentTagHelperTest.cs

@@ -0,0 +1,147 @@
+// 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 System.Collections.Generic;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Hosting;
+using Microsoft.AspNet.Razor.Runtime.TagHelpers;
+using Moq;
+using Xunit;
+
+namespace Microsoft.AspNet.Mvc.TagHelpers.Test
+{
+    public class EnvironmentTagHelperTest
+    {
+        [Theory]
+        [InlineData("Development", "Development")]
+        [InlineData("development", "Development")]
+        [InlineData("DEVELOPMENT", "Development")]
+        [InlineData(" development", "Development")]
+        [InlineData("development ", "Development")]
+        [InlineData(" development ", "Development")]
+        [InlineData("Development,Production", "Development")]
+        [InlineData("Production,Development", "Development")]
+        [InlineData("Development , Production", "Development")]
+        [InlineData("   Development,Production   ", "Development")]
+        [InlineData("Development ,  Production", "Development")]
+        [InlineData("Development\t,Production", "Development")]
+        [InlineData("Development,\tProduction", "Development")]
+        [InlineData(" Development,Production ", "Development")]
+        [InlineData("Development,Staging,Production", "Development")]
+        [InlineData("Staging,Development,Production", "Development")]
+        [InlineData("Staging,Production,Development", "Development")]
+        [InlineData("Test", "Test")]
+        [InlineData("Test,Staging", "Test")]
+        public void ShowsContentWhenCurrentEnvironmentIsSpecified(string namesAttribute, string environmentName)
+        {
+            ShouldShowContent(namesAttribute, environmentName);
+        }
+
+        [Theory]
+        [InlineData("", "Development")]
+        [InlineData(null, "Development")]
+        [InlineData("  ", "Development")]
+        [InlineData(", ", "Development")]
+        [InlineData("   , ", "Development")]
+        [InlineData("\t,\t", "Development")]
+        [InlineData(",", "Development")]
+        [InlineData(",,", "Development")]
+        [InlineData(",,,", "Development")]
+        [InlineData(",,, ", "Development")]
+        public void ShowsContentWhenNoEnvironmentIsSpecified(string namesAttribute, string environmentName)
+        {
+            ShouldShowContent(namesAttribute, environmentName);
+        }
+
+        [Theory]
+        [InlineData("Development", null)]
+        [InlineData("Development", "")]
+        [InlineData("Development", " ")]
+        [InlineData("Development", "  ")]
+        [InlineData("Development", "\t")]
+        [InlineData("Test", null)]
+        public void ShowsContentWhenCurrentEnvironmentIsNotSet(string namesAttribute, string environmentName)
+        {
+            ShouldShowContent(namesAttribute, environmentName);
+        }
+
+        [Theory]
+        [InlineData("NotDevelopment", "Development")]
+        [InlineData("NOTDEVELOPMENT", "Development")]
+        [InlineData("NotDevelopment,AlsoNotDevelopment", "Development")]
+        [InlineData("Doesn'tMatchAtAll", "Development")]
+        [InlineData("Development and a space", "Development")]
+        [InlineData("Development and a space,SomethingElse", "Development")]
+        public void DoesNotShowContentWhenCurrentEnvironmentIsNotSpecified(
+            string namesAttribute,
+            string environmentName)
+        {
+            // Arrange
+            var content = "content";
+            var context = MakeTagHelperContext(
+                attributes: new Dictionary<string, object> { { "names", namesAttribute } },
+                content: content);
+            var output = MakeTagHelperOutput("environment");
+            var hostingEnvironment = new Mock<IHostingEnvironment>();
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName);
+            hostingEnvironment.Object.EnvironmentName = environmentName;
+
+            // Act
+            var helper = new EnvironmentTagHelper
+            {
+                HostingEnvironment = hostingEnvironment.Object,
+                Names = namesAttribute
+            };
+            helper.Process(context, output);
+
+            // Assert
+            Assert.Null(output.TagName);
+            Assert.Null(output.PreContent);
+            Assert.Null(output.Content);
+            Assert.Null(output.PostContent);
+            Assert.True(output.ContentSet);
+        }
+
+        private void ShouldShowContent(string namesAttribute, string environmentName)
+        {
+            // Arrange
+            var content = "content";
+            var context = MakeTagHelperContext(
+                attributes: new Dictionary<string, object> { { "names", namesAttribute } },
+                content: content);
+            var output = MakeTagHelperOutput("environment");
+            var hostingEnvironment = new Mock<IHostingEnvironment>();
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName);
+            hostingEnvironment.Object.EnvironmentName = environmentName;
+
+            // Act
+            var helper = new EnvironmentTagHelper
+            {
+                HostingEnvironment = hostingEnvironment.Object,
+                Names = namesAttribute
+            };
+            helper.Process(context, output);
+
+            // Assert
+            Assert.Null(output.TagName);
+            Assert.False(output.ContentSet);
+        }
+
+        private TagHelperContext MakeTagHelperContext(
+            IDictionary<string, object> attributes = null,
+            string content = null)
+        {
+            attributes = attributes ?? new Dictionary<string, object>();
+
+            return new TagHelperContext(attributes, Guid.NewGuid().ToString("N"), () => Task.FromResult(content));
+        }
+
+        private TagHelperOutput MakeTagHelperOutput(string tagName, IDictionary<string, string> attributes = null)
+        {
+            attributes = attributes ?? new Dictionary<string, string>();
+            
+            return new TagHelperOutput(tagName, attributes);
+        }
+    }
+}

test/WebSites/MvcTagHelpersWebSite/Controllers/MvcTagHelper_HomeController.cs

@@ -136,5 +136,10 @@ namespace MvcTagHelpersWebSite.Controllers
             };
             return View(warehouse);
         }
+
+        public IActionResult Environment()
+        {
+            return View();
+        }
     }
 }

test/WebSites/MvcTagHelpersWebSite/Views/MvcTagHelper_Home/Environment.cshtml

@@ -0,0 +1,49 @@
+@addtaghelper "Microsoft.AspNet.Mvc.TagHelpers"
+
+<!doctype html>
+<html>
+<head>
+    <meta charset="utf-8" />
+    <title>Environment</title>
+</head>
+<body>
+
+    <h2>Environment Tag Helper Test</h2>
+
+    <ul>
+        <environment names="Development">
+            <li>This will show</li>
+        </environment>
+        <environment names="development">
+            <li>This will show</li>
+        </environment>
+        <environment names="Development,  Production">
+            <li>This will show</li>
+        </environment>
+        <environment names="Production, Development">
+            <li>This will show</li>
+        </environment>
+        <environment names="Local,Development, Production">
+            <li>This will show</li>
+        </environment>
+        <environment names="Development,">
+            <li>This will show</li>
+        </environment>
+        <environment>
+            <li>This will show</li>
+        </environment>
+        <environment names="">
+            <li>This will show</li>
+        </environment>
+        <environment names=" ">
+            <li>This will show</li>
+        </environment>
+        <environment names="Production">
+            <li>FAIL: This should NOT show</li>
+        </environment>
+        <environment names="Staging,Production">
+            <li>FAIL: This should NOT show</li>
+        </environment>
+    </ul>
+</body>
+</html>