Merge branch 'master' into merge/release/3.1-to-master\n\nCommit migrated from cf0d404196

src/HealthChecks/Abstractions/src/HealthReport.cs

@@ -34,7 +34,7 @@ namespace Microsoft.Extensions.Diagnostics.HealthChecks
 
         /// <summary>
         /// Gets a <see cref="HealthStatus"/> representing the aggregate status of all the health checks. The value of <see cref="Status"/>
-        /// will be the most servere status reported by a health check. If no checks were executed, the value is always <see cref="HealthStatus.Healthy"/>.
+        /// will be the most severe status reported by a health check. If no checks were executed, the value is always <see cref="HealthStatus.Healthy"/>.
         /// </summary>
         public HealthStatus Status { get; }
 

src/JSInterop/Microsoft.JSInterop.JS/src/Microsoft.JSInterop.JS.npmproj

@@ -2,7 +2,7 @@
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), Directory.Build.props))\Directory.Build.props" />
 
   <PropertyGroup>
-    <PackageId>@dotnet/jsinterop</PackageId>
+    <PackageId>@microsoft/dotnet-js-interop</PackageId>
     <IsPackable>true</IsPackable>
     <IsTestProject>false</IsTestProject>
     <IsShipping>true</IsShipping>

src/JSInterop/Microsoft.JSInterop.JS/src/package-lock.json

@@ -1,6 +1,6 @@
 {
-  "name": "@dotnet/jsinterop",
+  "name": "@microsoft/dotnet-js-interop",
-  "version": "3.0.0-dev",
+  "version": "5.0.0-dev",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

src/JSInterop/Microsoft.JSInterop.JS/src/package.json

@@ -1,6 +1,6 @@
 {
-  "name": "@dotnet/jsinterop",
+  "name": "@microsoft/dotnet-js-interop",
-  "version": "3.0.0-dev",
+  "version": "5.0.0-dev",
   "description": "Provides abstractions and features for interop between .NET and JavaScript code.",
   "main": "dist/Microsoft.JSInterop.js",
   "types": "dist/Microsoft.JSInterop.d.js",

src/JSInterop/startvs.cmd

@@ -0,0 +1,3 @@
+@ECHO OFF
+
+%~dp0..\..\startvs.cmd %~dp0JSInterop.slnf

src/Localization/Localization/src/ResourceManagerStringLocalizerFactory.cs

@@ -101,9 +101,8 @@ namespace Microsoft.Extensions.Localization
             else
             {
                 // This expectation is defined by dotnet's automatic resource storage.
-                // We have to conform to "{RootNamespace}.{ResourceLocation}.{FullTypeName - AssemblyName}".
+                // We have to conform to "{RootNamespace}.{ResourceLocation}.{FullTypeName - RootNamespace}".
-                var assemblyName = new AssemblyName(typeInfo.Assembly.FullName).Name;
+                return baseNamespace + "." + resourcesRelativePath + TrimPrefix(typeInfo.FullName, baseNamespace + ".");
-                return baseNamespace + "." + resourcesRelativePath + TrimPrefix(typeInfo.FullName, assemblyName + ".");
             }
         }
 

src/Localization/Localization/test/Microsoft.Extensions.Localization.RootNamespace.Tests/AssemblyInfo.cs

@@ -0,0 +1,5 @@
+using System.Reflection;
+using Microsoft.Extensions.Localization;
+
+[assembly: ResourceLocation("Resources")]
+[assembly: RootNamespace("LocalizationTest.Abc")]

src/Localization/Localization/test/Microsoft.Extensions.Localization.RootNamespace.Tests/Controllers/ValuesController.cs

@@ -0,0 +1,9 @@
+// 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.
+
+namespace LocalizationTest.Abc.Controllers
+{
+    public class ValuesController
+    {
+    }
+}

src/Localization/Localization/test/Microsoft.Extensions.Localization.RootNamespace.Tests/Microsoft.Extensions.Localization.RootNamespace.Tests.csproj

@@ -0,0 +1,26 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFrameworks>$(DefaultNetCoreTargetFramework);net472</TargetFrameworks>
+    <RootNamespace>LocalizationTest.Abc</RootNamespace>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Remove="NewFolder\**" />
+    <EmbeddedResource Remove="NewFolder\**" />
+    <None Remove="NewFolder\**" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Reference Include="Microsoft.Extensions.Localization.Abstractions" />
+    <Reference Include="Microsoft.Extensions.Localization" />
+    <Reference Include="Microsoft.Extensions.Logging.Abstractions" />
+    <Reference Include="Microsoft.Extensions.Logging.Testing" />
+    <Reference Include="Microsoft.Extensions.Options" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <EmbeddedResource Update="ValuesController.resx">
+      <Generator>ResXFileCodeGenerator</Generator>
+      <LastGenOutput>ValuesController.Designer.cs</LastGenOutput>
+    </EmbeddedResource>
+  </ItemGroup>
+</Project>

src/Localization/Localization/test/Microsoft.Extensions.Localization.RootNamespace.Tests/Resources/Controllers/ValuesController.resx

@@ -0,0 +1,123 @@
+<?xml version="1.0" encoding="utf-8"?>
+<root>
+  <!-- 
+    Microsoft ResX Schema 
+    
+    Version 2.0
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
+    Example:
+    
+    ... ado.net/XML headers & schema ...
+    <resheader name="resmimetype">text/microsoft-resx</resheader>
+    <resheader name="version">2.0</resheader>
+    <resheader name="reader">System.Resources.ResXResourceReader, System.Windows.Forms, ...</resheader>
+    <resheader name="writer">System.Resources.ResXResourceWriter, System.Windows.Forms, ...</resheader>
+    <data name="Name1"><value>this is my long string</value><comment>this is a comment</comment></data>
+    <data name="Color1" type="System.Drawing.Color, System.Drawing">Blue</data>
+    <data name="Bitmap1" mimetype="application/x-microsoft.net.object.binary.base64">
+        <value>[base64 mime encoded serialized .NET Framework object]</value>
+    </data>
+    <data name="Icon1" type="System.Drawing.Icon, System.Drawing" mimetype="application/x-microsoft.net.object.bytearray.base64">
+        <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
+        <comment>This is a comment</comment>
+    </data>
+                
+    There are any number of "resheader" rows that contain simple 
+    name/value pairs.
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
+    mimetype set.
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
+    extensible. For a given mimetype the value must be set accordingly:
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
+    read any of the formats listed below.
+    
+    mimetype: application/x-microsoft.net.object.binary.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
+            : and then encoded with base64 encoding.
+    
+    mimetype: application/x-microsoft.net.object.soap.base64
+    value   : The object must be serialized with 
+            : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
+            : and then encoded with base64 encoding.
+
+    mimetype: application/x-microsoft.net.object.bytearray.base64
+    value   : The object must be serialized into a byte array 
+            : using a System.ComponentModel.TypeConverter
+            : and then encoded with base64 encoding.
+    -->
+  <xsd:schema id="root" xmlns="" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
+    <xsd:import namespace="http://www.w3.org/XML/1998/namespace" />
+    <xsd:element name="root" msdata:IsDataSet="true">
+      <xsd:complexType>
+        <xsd:choice maxOccurs="unbounded">
+          <xsd:element name="metadata">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" />
+              </xsd:sequence>
+              <xsd:attribute name="name" use="required" type="xsd:string" />
+              <xsd:attribute name="type" type="xsd:string" />
+              <xsd:attribute name="mimetype" type="xsd:string" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="assembly">
+            <xsd:complexType>
+              <xsd:attribute name="alias" type="xsd:string" />
+              <xsd:attribute name="name" type="xsd:string" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="data">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+                <xsd:element name="comment" type="xsd:string" minOccurs="0" msdata:Ordinal="2" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" msdata:Ordinal="1" />
+              <xsd:attribute name="type" type="xsd:string" msdata:Ordinal="3" />
+              <xsd:attribute name="mimetype" type="xsd:string" msdata:Ordinal="4" />
+              <xsd:attribute ref="xml:space" />
+            </xsd:complexType>
+          </xsd:element>
+          <xsd:element name="resheader">
+            <xsd:complexType>
+              <xsd:sequence>
+                <xsd:element name="value" type="xsd:string" minOccurs="0" msdata:Ordinal="1" />
+              </xsd:sequence>
+              <xsd:attribute name="name" type="xsd:string" use="required" />
+            </xsd:complexType>
+          </xsd:element>
+        </xsd:choice>
+      </xsd:complexType>
+    </xsd:element>
+  </xsd:schema>
+  <resheader name="resmimetype">
+    <value>text/microsoft-resx</value>
+  </resheader>
+  <resheader name="version">
+    <value>2.0</value>
+  </resheader>
+  <resheader name="reader">
+    <value>System.Resources.ResXResourceReader, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <resheader name="writer">
+    <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
+  </resheader>
+  <data name="String1" xml:space="preserve">
+    <value>ValFromResource</value>
+  </data>
+</root>

src/Localization/Localization/test/Microsoft.Extensions.Localization.RootNamespace.Tests/StringLocalizerOfTRootNamespaceTest.cs

@@ -0,0 +1,26 @@
+// 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 LocalizationTest.Abc.Controllers;
+using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
+using Moq;
+using Xunit;
+
+namespace Microsoft.Extensions.Localization.RootNamespace.Tests
+{
+    public class StringLocalizerOfTRootNamespaceTest
+    {
+        [Fact]
+        public void RootNamespace()
+        {
+            var locOptions = new LocalizationOptions();
+            var options = new Mock<IOptions<LocalizationOptions>>();
+            options.Setup(o => o.Value).Returns(locOptions);
+            var factory = new ResourceManagerStringLocalizerFactory(options.Object, NullLoggerFactory.Instance);
+
+            var valuesLoc = factory.Create(typeof(ValuesController));
+            Assert.Equal("ValFromResource", valuesLoc["String1"]);
+        }
+    }
+}

src/Localization/Localization/test/Microsoft.Extensions.Localization.Tests/Model.cs

@@ -0,0 +1,8 @@
+// This namespace for test resources with alternative RootNamespace
+namespace MyNamespace
+{
+    public class Model
+    {
+        
+    }
+}

src/Localization/Localization/test/Microsoft.Extensions.Localization.Tests/ResourceManagerStringLocalizerFactoryTest.cs

@@ -7,6 +7,7 @@ using System.Reflection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Extensions.Options;
+using MyNamespace;
 using Moq;
 using Xunit;
 
@@ -132,7 +133,7 @@ namespace Microsoft.Extensions.Localization.Tests
             var loggerFactory = NullLoggerFactory.Instance;
 
             var resourcePath = Path.Combine("My", "Resources");
-            var rootNamespace = "MyNamespace";
+            var rootNamespace = nameof(MyNamespace);
             var rootNamespaceAttribute = new RootNamespaceAttribute(rootNamespace);
 
             var typeFactory = new TestResourceManagerStringLocalizerFactory(
@@ -141,12 +142,13 @@ namespace Microsoft.Extensions.Localization.Tests
                 rootNamespaceAttribute: rootNamespaceAttribute,
                 loggerFactory: loggerFactory);
 
-            var type = typeof(ResourceManagerStringLocalizerFactoryTest);
+            var type = typeof(Model);
+
             // Act
             typeFactory.Create(type);
 
             // Assert
-            Assert.Equal($"Microsoft.Extensions.Localization.Tests.ResourceManagerStringLocalizerFactoryTest", typeFactory.BaseName);
+            Assert.Equal($"{rootNamespace}.{nameof(Model)}", typeFactory.BaseName);
         }
 
         [Fact]
@@ -159,7 +161,7 @@ namespace Microsoft.Extensions.Localization.Tests
             var loggerFactory = NullLoggerFactory.Instance;
 
             var resourcePath = Path.Combine("My", "Resources");
-            var rootNamespace = "MyNamespace";
+            var rootNamespace = nameof(MyNamespace);
             var resourceLocationAttribute = new ResourceLocationAttribute(resourcePath);
             var rootNamespaceAttribute = new RootNamespaceAttribute(rootNamespace);
 
@@ -169,12 +171,13 @@ namespace Microsoft.Extensions.Localization.Tests
                 rootNamespaceAttribute,
                 loggerFactory);
 
-            var type = typeof(ResourceManagerStringLocalizerFactoryTest);
+            var type = typeof(Model);
+
             // Act
             typeFactory.Create(type);
 
             // Assert
-            Assert.Equal($"MyNamespace.My.Resources.ResourceManagerStringLocalizerFactoryTest", typeFactory.BaseName);
+            Assert.Equal($"{rootNamespace}.My.Resources.{nameof(Model)}", typeFactory.BaseName);
         }
 
         [Fact]

src/Shared/BenchmarkRunner/DefaultCoreConfig.cs

@@ -34,6 +34,8 @@ namespace BenchmarkDotNet.Attributes
                 .With(CsProjCoreToolchain.From(new NetCoreAppSettings("netcoreapp3.0", null, ".NET Core 3.0")))
 #elif NETCOREAPP3_1
                 .With(CsProjCoreToolchain.From(new NetCoreAppSettings("netcoreapp3.1", null, ".NET Core 3.1")))
+#elif NETCOREAPP5_0
+                .With(CsProjCoreToolchain.From(new NetCoreAppSettings("netcoreapp5.0", null, ".NET Core 5.0")))
 #else
 #error Target frameworks need to be updated.
 #endif

src/Shared/TypeNameHelper/TypeNameHelper.cs

@@ -7,7 +7,7 @@ using System.Collections.Generic;
 
 namespace Microsoft.Extensions.Internal
 {
-    internal class TypeNameHelper
+    internal static class TypeNameHelper
     {
         private const char DefaultNestedTypeDelimiter = '+';
 

src/Testing/ref/Microsoft.AspNetCore.Testing.net46.cs

@@ -170,6 +170,13 @@ namespace Microsoft.AspNetCore.Testing
         System.Threading.Tasks.Task OnTestStartAsync(Microsoft.AspNetCore.Testing.TestContext context, System.Threading.CancellationToken cancellationToken);
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Method, AllowMultiple=true)]
+    public partial class MaximumOSVersionAttribute : System.Attribute, Microsoft.AspNetCore.Testing.ITestCondition
+    {
+        public MaximumOSVersionAttribute(Microsoft.AspNetCore.Testing.OperatingSystems operatingSystem, string maxVersion) { }
+        public bool IsMet { get { throw null; } }
+        public string SkipReason { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+    }
+    [System.AttributeUsageAttribute(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Method, AllowMultiple=true)]
     public partial class MinimumOSVersionAttribute : System.Attribute, Microsoft.AspNetCore.Testing.ITestCondition
     {
         public MinimumOSVersionAttribute(Microsoft.AspNetCore.Testing.OperatingSystems operatingSystem, string minVersion) { }
@@ -319,9 +326,11 @@ namespace Microsoft.AspNetCore.Testing
     public static partial class WindowsVersions
     {
         public const string Win10 = "10.0";
+        public const string Win10_19H1 = "10.0.18362";
         public const string Win10_19H2 = "10.0.18363";
-        public const string Win10_20H1 = "10.0.18990";
+        public const string Win10_20H1 = "10.0.19033";
         public const string Win10_RS4 = "10.0.17134";
+        public const string Win10_RS5 = "10.0.17763";
         public const string Win2008R2 = "6.1";
         public const string Win7 = "6.1";
         public const string Win8 = "6.2";

src/Testing/ref/Microsoft.AspNetCore.Testing.netstandard2.0.cs

@@ -170,6 +170,13 @@ namespace Microsoft.AspNetCore.Testing
         System.Threading.Tasks.Task OnTestStartAsync(Microsoft.AspNetCore.Testing.TestContext context, System.Threading.CancellationToken cancellationToken);
     }
     [System.AttributeUsageAttribute(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Method, AllowMultiple=true)]
+    public partial class MaximumOSVersionAttribute : System.Attribute, Microsoft.AspNetCore.Testing.ITestCondition
+    {
+        public MaximumOSVersionAttribute(Microsoft.AspNetCore.Testing.OperatingSystems operatingSystem, string maxVersion) { }
+        public bool IsMet { get { throw null; } }
+        public string SkipReason { [System.Runtime.CompilerServices.CompilerGeneratedAttribute] get { throw null; } [System.Runtime.CompilerServices.CompilerGeneratedAttribute] set { } }
+    }
+    [System.AttributeUsageAttribute(System.AttributeTargets.Assembly | System.AttributeTargets.Class | System.AttributeTargets.Method, AllowMultiple=true)]
     public partial class MinimumOSVersionAttribute : System.Attribute, Microsoft.AspNetCore.Testing.ITestCondition
     {
         public MinimumOSVersionAttribute(Microsoft.AspNetCore.Testing.OperatingSystems operatingSystem, string minVersion) { }
@@ -319,9 +326,11 @@ namespace Microsoft.AspNetCore.Testing
     public static partial class WindowsVersions
     {
         public const string Win10 = "10.0";
+        public const string Win10_19H1 = "10.0.18362";
         public const string Win10_19H2 = "10.0.18363";
-        public const string Win10_20H1 = "10.0.18990";
+        public const string Win10_20H1 = "10.0.19033";
         public const string Win10_RS4 = "10.0.17134";
+        public const string Win10_RS5 = "10.0.17763";
         public const string Win2008R2 = "6.1";
         public const string Win7 = "6.1";
         public const string Win8 = "6.2";

src/Testing/src/xunit/MaximumOSVersionAttribute.cs

@@ -0,0 +1,83 @@
+// 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 System;
+using System.Runtime.InteropServices;
+
+namespace Microsoft.AspNetCore.Testing
+{
+    /// <summary>
+    /// Skips a test if the OS is the given type (Windows) and the OS version is greater than specified.
+    /// E.g. Specifying Window 8 skips on Win 10, but not on Linux. Combine with OSSkipConditionAttribute as needed.
+    /// </summary>
+    [AttributeUsage(AttributeTargets.Method | AttributeTargets.Class | AttributeTargets.Assembly, AllowMultiple = true)]
+    public class MaximumOSVersionAttribute : Attribute, ITestCondition
+    {
+        private readonly OperatingSystems _targetOS;
+        private readonly Version _maxVersion;
+        private readonly OperatingSystems _currentOS;
+        private readonly Version _currentVersion;
+        private readonly bool _skip;
+
+        public MaximumOSVersionAttribute(OperatingSystems operatingSystem, string maxVersion) :
+            this(operatingSystem, Version.Parse(maxVersion), GetCurrentOS(), GetCurrentOSVersion())
+        {
+        }
+
+        // to enable unit testing
+        internal MaximumOSVersionAttribute(OperatingSystems targetOS, Version maxVersion, OperatingSystems currentOS, Version currentVersion)
+        {
+            if (targetOS != OperatingSystems.Windows)
+            {
+                throw new NotImplementedException("Max version support is only implemented for Windows.");
+            }
+            _targetOS = targetOS;
+            _maxVersion = maxVersion;
+            _currentOS = currentOS;
+            // We drop the 4th field because it is not significant and it messes up the comparisons.
+            _currentVersion = new Version(currentVersion.Major, currentVersion.Minor,
+                // Major and Minor are required by the parser, but if Build isn't specified then it returns -1
+                // which the constructor rejects.
+                currentVersion.Build == -1 ? 0 : currentVersion.Build);
+
+            // Do not skip other OS's, Use OSSkipConditionAttribute or a separate MaximumOsVersionAttribute for that.
+            _skip = _targetOS == _currentOS && _maxVersion < _currentVersion;
+            SkipReason = $"This test requires {_targetOS} {_maxVersion} or earlier.";
+        }
+
+        // Since a test would be executed only if 'IsMet' is true, return false if we want to skip
+        public bool IsMet => !_skip;
+
+        public string SkipReason { get; set; }
+
+        private static OperatingSystems GetCurrentOS()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return OperatingSystems.Windows;
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux))
+            {
+                return OperatingSystems.Linux;
+            }
+            else if (RuntimeInformation.IsOSPlatform(OSPlatform.OSX))
+            {
+                return OperatingSystems.MacOSX;
+            }
+            throw new PlatformNotSupportedException();
+        }
+
+        static private Version GetCurrentOSVersion()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                return Environment.OSVersion.Version;
+            }
+            else
+            {
+                // Not implemented, but this will still be called before the OS check happens so don't throw.
+                return new Version(0, 0);
+            }
+        }
+    }
+}

src/Testing/src/xunit/WindowsVersions.cs

@@ -23,14 +23,24 @@ namespace Microsoft.AspNetCore.Testing
         /// </summary>
         public const string Win10_RS4 = "10.0.17134";
 
+        /// <summary>
+        /// 1809, RS5, 17763
+        /// </summary>
+        public const string Win10_RS5 = "10.0.17763";
+
+        /// <summary>
+        /// 1903, 19H1, 18362
+        /// </summary>
+        public const string Win10_19H1 = "10.0.18362";
+
         /// <summary>
         /// 1909, 19H2, 18363
         /// </summary>
         public const string Win10_19H2 = "10.0.18363";
 
         /// <summary>
-        /// _, 20H2, 18990
+        /// 2004, 20H1, 19033
         /// </summary>
-        public const string Win10_20H1 = "10.0.18990";
+        public const string Win10_20H1 = "10.0.19033";
     }
 }

src/Testing/test/MaximumOSVersionAttributeTest.cs

@@ -0,0 +1,89 @@
+// 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 System;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Testing
+{
+    public class MaximumOSVersionAttributeTest
+    {
+        [Fact]
+        public void Linux_ThrowsNotImplemeneted()
+        {
+            Assert.Throws<NotImplementedException>(() => new MaximumOSVersionAttribute(OperatingSystems.Linux, "2.5"));
+        }
+
+        [Fact]
+        public void Mac_ThrowsNotImplemeneted()
+        {
+            Assert.Throws<NotImplementedException>(() => new MaximumOSVersionAttribute(OperatingSystems.MacOSX, "2.5"));
+        }
+
+        [Fact]
+        public void WindowsOrLinux_ThrowsNotImplemeneted()
+        {
+            Assert.Throws<NotImplementedException>(() => new MaximumOSVersionAttribute(OperatingSystems.Linux | OperatingSystems.Windows, "2.5"));
+        }
+
+        [Fact]
+        public void DoesNotSkip_ShortVersions()
+        {
+            var osSkipAttribute = new MaximumOSVersionAttribute(
+                OperatingSystems.Windows,
+                new Version("2.5"),
+                OperatingSystems.Windows,
+                new Version("2.0"));
+
+            Assert.True(osSkipAttribute.IsMet);
+        }
+
+        [Fact]
+        public void DoesNotSkip_EarlierVersions()
+        {
+            var osSkipAttribute = new MaximumOSVersionAttribute(
+                OperatingSystems.Windows,
+                new Version("2.5.9"),
+                OperatingSystems.Windows,
+                new Version("2.0.10.12"));
+
+            Assert.True(osSkipAttribute.IsMet);
+        }
+
+        [Fact]
+        public void DoesNotSkip_SameVersion()
+        {
+            var osSkipAttribute = new MaximumOSVersionAttribute(
+                OperatingSystems.Windows,
+                new Version("2.5.10"),
+                OperatingSystems.Windows,
+                new Version("2.5.10.12"));
+
+            Assert.True(osSkipAttribute.IsMet);
+        }
+
+        [Fact]
+        public void Skip_LaterVersion()
+        {
+            var osSkipAttribute = new MaximumOSVersionAttribute(
+                OperatingSystems.Windows,
+                new Version("2.5.11"),
+                OperatingSystems.Windows,
+                new Version("3.0.10.12"));
+
+            Assert.False(osSkipAttribute.IsMet);
+        }
+
+        [Fact]
+        public void DoesNotSkip_WhenOnlyVersionsMatch()
+        {
+            var osSkipAttribute = new MaximumOSVersionAttribute(
+                OperatingSystems.Windows,
+                new Version("2.5.10.12"),
+                OperatingSystems.Linux,
+                new Version("2.5.10.12"));
+
+            Assert.True(osSkipAttribute.IsMet);
+        }
+    }
+}

src/Testing/test/MaximumOSVersionTest.cs

@@ -0,0 +1,90 @@
+// 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 System;
+using System.Runtime.InteropServices;
+using Microsoft.Win32;
+using Xunit;
+
+namespace Microsoft.AspNetCore.Testing
+{
+    [OSSkipCondition(OperatingSystems.Linux | OperatingSystems.MacOSX)]
+    public class MaximumOSVersionTest
+    {
+        [ConditionalFact]
+        [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win7)]
+        public void RunTest_Win7DoesRunOnWin7()
+        {
+            Assert.True(
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
+                Environment.OSVersion.Version.ToString().StartsWith("6.1"),
+                "Test should only be running on Win7 or Win2008R2.");
+        }
+
+        [ConditionalTheory]
+        [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win7)]
+        [InlineData(1)]
+        public void RunTheory_Win7DoesRunOnWin7(int arg)
+        {
+            Assert.True(
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
+                Environment.OSVersion.Version.ToString().StartsWith("6.1"),
+                "Test should only be running on Win7 or Win2008R2.");
+        }
+
+        [ConditionalFact]
+        [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win10_RS4)]
+        [OSSkipCondition(OperatingSystems.Linux | OperatingSystems.MacOSX)]
+        public void RunTest_Win10_RS4()
+        {
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Windows));
+            var versionKey = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
+            Assert.NotNull(versionKey);
+            var currentVersion = (string)versionKey.GetValue("CurrentBuildNumber");
+            Assert.NotNull(currentVersion);
+            Assert.True(17134 >= int.Parse(currentVersion));
+        }
+
+        [ConditionalFact]
+        [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win10_19H2)]
+        [OSSkipCondition(OperatingSystems.Linux | OperatingSystems.MacOSX)]
+        public void RunTest_Win10_19H2()
+        {
+            Assert.True(RuntimeInformation.IsOSPlatform(OSPlatform.Windows));
+            var versionKey = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Microsoft\Windows NT\CurrentVersion");
+            Assert.NotNull(versionKey);
+            var currentVersion = (string)versionKey.GetValue("CurrentBuildNumber");
+            Assert.NotNull(currentVersion);
+            Assert.True(18363 >= int.Parse(currentVersion));
+        }
+    }
+
+    [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win7)]
+    [OSSkipCondition(OperatingSystems.Linux | OperatingSystems.MacOSX)]
+    public class OSMaxVersionClassTest
+    {
+        [ConditionalFact]
+        public void TestSkipClass_Win7DoesRunOnWin7()
+        {
+            Assert.True(
+                RuntimeInformation.IsOSPlatform(OSPlatform.Windows) &&
+                Environment.OSVersion.Version.ToString().StartsWith("6.1"),
+                "Test should only be running on Win7 or Win2008R2.");
+        }
+    }
+
+    // Let this one run cross plat just to check the constructor logic.
+    [MaximumOSVersion(OperatingSystems.Windows, WindowsVersions.Win7)]
+    public class OSMaxVersionCrossPlatTest
+    {
+        [ConditionalFact]
+        public void TestSkipClass_Win7DoesRunOnWin7()
+        {
+            if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
+            {
+                Assert.True(Environment.OSVersion.Version.ToString().StartsWith("6.1"),
+                    "Test should only be running on Win7 or Win2008R2.");
+            }
+        }
+    }
+}