Add include and exclude attributes to EnvironmentTagHelper

Addresses #5671

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

@@ -11,6 +11,8 @@ namespace Microsoft.AspNetCore.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"/>.
+    /// If the environment is not listed in the specified <see cref="Names"/> or <see cref="Include"/>, 
+    /// or if it is in <see cref="Exclude"/>, the content will not be rendered.
     /// </summary>
     public class EnvironmentTagHelper : TagHelper
     {
@@ -30,6 +32,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
 
         /// <summary>
         /// A comma separated list of environment names in which the content should be rendered.
+        /// If the current environment is also in the <see cref="Exclude"/> list, the content will not be rendered.
         /// </summary>
         /// <remarks>
         /// The specified environment names are compared case insensitively to the current value of
@@ -37,6 +40,25 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
         /// </remarks>
         public string Names { get; set; }
 
+        /// <summary>
+        /// A comma separated list of environment names in which the content should be rendered.
+        /// If the current environment is also in the <see cref="Exclude"/> list, the content will not be rendered.
+        /// </summary>
+        /// <remarks>
+        /// The specified environment names are compared case insensitively to the current value of
+        /// <see cref="IHostingEnvironment.EnvironmentName"/>.
+        /// </remarks>
+        public string Include { get; set; }
+
+        /// <summary>
+        /// A comma separated list of environment names in which the content will not be rendered.
+        /// </summary>
+        /// <remarks>
+        /// The specified environment names are compared case insensitively to the current value of
+        /// <see cref="IHostingEnvironment.EnvironmentName"/>.
+        /// </remarks>
+        public string Exclude { get; set; }
+
         protected IHostingEnvironment HostingEnvironment { get; }
 
         /// <inheritdoc />
@@ -55,7 +77,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
             // Always strip the outer tag name as we never want <environment> to render
             output.TagName = null;
 
-            if (string.IsNullOrWhiteSpace(Names))
+            if (string.IsNullOrWhiteSpace(Names) && string.IsNullOrWhiteSpace(Include) && string.IsNullOrWhiteSpace(Exclude))
             {
                 // No names specified, do nothing
                 return;
@@ -68,27 +90,67 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers
                 return;
             }
 
-            var tokenizer = new StringTokenizer(Names, NameSeparator);
+            if (Exclude != null)
-            var hasEnvironments = false;
-            foreach (var item in tokenizer)
             {
-                var environment = item.Trim();
+                var tokenizer = new StringTokenizer(Exclude, NameSeparator);
-                if (environment.HasValue && environment.Length > 0)
+                foreach (var item in tokenizer)
                 {
-                    hasEnvironments = true;
+                    var environment = item.Trim();
-                    if (environment.Equals(currentEnvironmentName, StringComparison.OrdinalIgnoreCase))
+                    if (environment.HasValue && environment.Length > 0)
                     {
-                        // Matching environment name found, do nothing
+                        if (environment.Equals(currentEnvironmentName, StringComparison.OrdinalIgnoreCase))
-                        return;
+                        {
+                            // Matching environment name found, suppress output
+                            output.SuppressOutput();
+                            return;
+                        }
+                    }
+                }
+            }
+
+            var hasEnvironments = false;
+            if (Names != null)
+            {
+                var tokenizer = new StringTokenizer(Names, NameSeparator);
+                foreach (var item in tokenizer)
+                {
+                    var environment = item.Trim();
+                    if (environment.HasValue && environment.Length > 0)
+                    {
+                        hasEnvironments = true;
+                        if (environment.Equals(currentEnvironmentName, StringComparison.OrdinalIgnoreCase))
+                        {
+                            // Matching environment name found, do nothing
+                            return;
+                        }
+                    }
+                }
+            }
+
+            if (Include != null)
+            {
+                var tokenizer = new StringTokenizer(Include, NameSeparator);
+                foreach (var item in tokenizer)
+                {
+                    var environment = item.Trim();
+                    if (environment.HasValue && environment.Length > 0)
+                    {
+                        hasEnvironments = true;
+                        if (environment.Equals(currentEnvironmentName, StringComparison.OrdinalIgnoreCase))
+                        {
+                            // Matching environment name found, do nothing
+                            return;
+                        }
                     }
                 }
             }
 
             if (hasEnvironments)
             {
-                // This instance had at least one non-empty environment specified but none of these
+                // This instance had at least one non-empty environment (names or include) specified but none of these
                 // environments matched the current environment. Suppress the output in this case.
                 output.SuppressOutput();
+                return;
             }
         }
     }

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

@@ -66,6 +66,94 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers.Test
             ShouldShowContent(namesAttribute, environmentName);
         }
 
+        [Theory]
+        [InlineData("", "", "")]
+        [InlineData("", null, "Test")]
+        [InlineData("Development", "", "")]
+        [InlineData("", "Development, Test", "")]
+        [InlineData(null, "development, TEST", "Test")]
+        [InlineData("Development", "", "Test")]
+        [InlineData("Development", "Test, Development", "")]
+        [InlineData("Test", "DEVELOPMENT", null)]
+        [InlineData("Development", "Test", "")]
+        [InlineData("Development", null, "Test")]
+        [InlineData("Development", "Test", "Test")]
+        [InlineData("Test", "Development", "Test")]
+        public void ShouldShowContent_IncludeExcludeSpecified(string namesAttribute, string includeAttribute, string excludeAttribute)
+        {
+            // Arrange
+            var content = "content";
+            var context = MakeTagHelperContext(
+                attributes: new TagHelperAttributeList {
+                    { "names", namesAttribute },
+                    { "include", includeAttribute },
+                    { "exclude", excludeAttribute },
+                });
+            var output = MakeTagHelperOutput("environment", childContent: content);
+            var hostingEnvironment = new Mock<IHostingEnvironment>();
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName, "Development");
+
+            // Act
+            var helper = new EnvironmentTagHelper(hostingEnvironment.Object)
+            {
+                Names = namesAttribute,
+                Include = includeAttribute,
+                Exclude = excludeAttribute,
+            };
+            helper.Process(context, output);
+
+            // Assert
+            Assert.Null(output.TagName);
+            Assert.False(output.IsContentModified);
+        }
+
+        [Theory]
+        [InlineData(null, "", "Development")]
+        [InlineData("", "Development", "development")]
+        [InlineData("", "Test", "Development, test")]
+        [InlineData("Development", "", "Development")]
+        [InlineData("Test", "", "Development")]
+        [InlineData("Development", "Development", "DEVELOPMENT, TEST")]
+        [InlineData("Development", "Test", "Development")]
+        [InlineData("Test", "Development", "Development")]
+        [InlineData("Test", "Test", "Development")]
+        [InlineData("", "Test", "Test")]
+        [InlineData("Test", null, "Test")]
+        [InlineData("Test", "Test", "Test")]
+        [InlineData("", "Test", null)]
+        [InlineData("Test", "", "")]
+        [InlineData("Test", "Test", null)]
+        public void DoesNotShowContent_IncludeExcludeSpecified(string namesAttribute, string includeAttribute, string excludeAttribute)
+        {
+            // Arrange
+            var content = "content";
+            var context = MakeTagHelperContext(
+                attributes: new TagHelperAttributeList {
+                    { "names", namesAttribute },
+                    { "include", includeAttribute },
+                    { "exclude", excludeAttribute },
+                });
+            var output = MakeTagHelperOutput("environment", childContent: content);
+            var hostingEnvironment = new Mock<IHostingEnvironment>();
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName, "Development");
+
+            // Act
+            var helper = new EnvironmentTagHelper(hostingEnvironment.Object)
+            {
+                Names = namesAttribute,
+                Include = includeAttribute,
+                Exclude = excludeAttribute,
+            };
+            helper.Process(context, output);
+
+            // Assert
+            Assert.Null(output.TagName);
+            Assert.Empty(output.PreContent.GetContent());
+            Assert.True(output.Content.GetContent().Length == 0);
+            Assert.Empty(output.PostContent.GetContent());
+            Assert.True(output.IsContentModified);
+        }
+
         [Theory]
         [InlineData("NotDevelopment", "Development")]
         [InlineData("NOTDEVELOPMENT", "Development")]
@@ -82,8 +170,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers.Test
             var context = MakeTagHelperContext(attributes: new TagHelperAttributeList { { "names", namesAttribute } });
             var output = MakeTagHelperOutput("environment", childContent: content);
             var hostingEnvironment = new Mock<IHostingEnvironment>();
-            hostingEnvironment.SetupProperty(h => h.EnvironmentName);
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName, environmentName);
-            hostingEnvironment.Object.EnvironmentName = environmentName;
 
             // Act
             var helper = new EnvironmentTagHelper(hostingEnvironment.Object)
@@ -108,8 +195,7 @@ namespace Microsoft.AspNetCore.Mvc.TagHelpers.Test
                 attributes: new TagHelperAttributeList { { "names", namesAttribute } });
             var output = MakeTagHelperOutput("environment", childContent: content);
             var hostingEnvironment = new Mock<IHostingEnvironment>();
-            hostingEnvironment.SetupProperty(h => h.EnvironmentName);
+            hostingEnvironment.SetupProperty(h => h.EnvironmentName, environmentName);
-            hostingEnvironment.Object.EnvironmentName = environmentName;
 
             // Act
             var helper = new EnvironmentTagHelper(hostingEnvironment.Object)