Added unit tests

- #1553

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

@@ -24,7 +24,7 @@ public class EnvironmentTagHelper : TagHelper
         // Protected to ensure subclasses are correctly activated. Internal for ease of use when testing.
         [Activate]
         protected internal IHostingEnvironment HostingEnvironment { get; set; }
-
+        
         public override void Process(TagHelperContext context, TagHelperOutput output)
         {
             // Always strip the outer tag name as we never want <environment> to render
@@ -36,7 +36,9 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
                 return;
             }
 
-            var environments = Names.Split(_nameSeparator, StringSplitOptions.RemoveEmptyEntries);
+            var environments = Names.Split(_nameSeparator, StringSplitOptions.RemoveEmptyEntries)
+                                    .Where(name => !string.IsNullOrWhiteSpace(name))
+                                    .ToArray();
 
             if (environments.Length == 0)
             {

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

@@ -0,0 +1,124 @@
+// 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")]
+        [InlineData("development")]
+        [InlineData("DEVELOPMENT")]
+        [InlineData(" development")]
+        [InlineData("development ")]
+        [InlineData(" development ")]
+        [InlineData("Development,Production")]
+        [InlineData("Production,Development")]
+        [InlineData("Development , Production")]
+        [InlineData(" Development,Production ")]
+        [InlineData("Development,Staging,Production")]
+        [InlineData("Staging,Development,Production")]
+        [InlineData("Staging,Production,Development")]
+        public void ShowsContentWhenCurrentEnvironmentIsSpecified(string namesAttribute)
+        {
+            ShouldShowContent(namesAttribute);
+        }
+
+        [Theory]
+        [InlineData("")]
+        [InlineData(null)]
+        [InlineData("  ")]
+        [InlineData(", ")]
+        [InlineData("   , ")]
+        [InlineData(",")]
+        [InlineData(",,")]
+        [InlineData(",,,")]
+        [InlineData(",,, ")]
+        public void ShowsContentWhenNoEnvironmentIsSpecified(string namesAttribute)
+        {
+            ShouldShowContent(namesAttribute);
+        }
+
+        [Theory]
+        [InlineData("NotDevelopment")]
+        [InlineData("NOTDEVELOPMENT")]
+        [InlineData("NotDevelopment,AlsoNotDevelopment")]
+        [InlineData("Doesn'tMatchAtAll")]
+        [InlineData("Development and a space")]
+        [InlineData("Development and a space,SomethingElse")]
+        public void DoesNotShowContentWhenCurrentEnvironmentIsNotSpecified(string namesAttribute)
+        {
+            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 = "Development";
+
+            var helper = new EnvironmentTagHelper
+            {
+                HostingEnvironment = hostingEnvironment.Object,
+                Names = namesAttribute
+            };
+            helper.Process(context, output);
+
+            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)
+        {
+            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 = "Development";
+
+            var helper = new EnvironmentTagHelper
+            {
+                HostingEnvironment = hostingEnvironment.Object,
+                Names = namesAttribute
+            };
+            helper.Process(context, output);
+
+            Assert.Null(output.TagName);
+            Assert.False(output.ContentSet);
+        }
+
+        private TagHelperContext MakeTagHelperContext(IDictionary<string, object> attributes = null, string content = null)
+        {
+            if (attributes == null)
+            {
+                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)
+        {
+            if (attributes == null)
+            {
+                attributes = new Dictionary<string, string>();
+            }
+
+            return new TagHelperOutput(tagName, attributes);
+        }
+    }
+}