Add OSVersion APIs to .NET Core

The contract System.Runtime.InteropServices.RuntimeInformation provides
RuntimeInformation type that has methods to query for underlying OS
information at runtime. The OS information is expressed by the OSPlatform type.
Reference issue: dotnet\corefx#1017, API Review done on 2015\06\09.

Author: Lakshmi Priya Sekar

src/System.Runtime.Environment/src/OSName.cs

@@ -3,9 +3,9 @@ Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 14
 VisualStudioVersion = 14.0.22609.0
 MinimumVisualStudioVersion = 10.0.40219.1
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.Runtime.Environment", "src\System.Runtime.Environment.csproj", "{F9DF2357-81B4-4317-908E-512DA9395583}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.Runtime.InteropServices.RuntimeInformation", "src\System.Runtime.InteropServices.RuntimeInformation.csproj", "{F9DF2357-81B4-4317-908E-512DA9395583}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.Runtime.Environment.Tests", "tests\System.Runtime.Environment.Tests.csproj", "{9B4D1DA9-AA4C-428F-9F66-D45C924025A5}"
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "System.Runtime.InteropServices.RuntimeInformation.Tests", "tests\System.Runtime.InteropServices.RuntimeInformation.Tests.csproj", "{9B4D1DA9-AA4C-428F-9F66-D45C924025A5}"
 EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution

src/System.Runtime.Environment/tests/CheckPlatformTests.cs

@@ -0,0 +1,90 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace System.Runtime.InteropServices
+{
+    public struct OSPlatform : IEquatable<OSPlatform>
+    {
+        private readonly string _osPlatform;
+
+        private const string WindowsName = "WINDOWS";
+        private const string LinuxName = "LINUX";
+        private const string OSXName = "OSX";
+
+        private static readonly OSPlatform s_windows = new OSPlatform(WindowsName);
+        private static readonly OSPlatform s_linux = new OSPlatform(LinuxName);
+        private static readonly OSPlatform s_osx = new OSPlatform(OSXName);
+
+        public static OSPlatform Windows
+        {
+            get
+            {
+                return s_windows;
+            }
+        }
+
+        public static OSPlatform Linux
+        {
+            get
+            {
+                return s_linux;
+            }
+        }
+
+        public static OSPlatform OSX
+        {
+            get
+            {
+                return s_osx;
+            }
+        }
+
+        private OSPlatform(string osPlatform)
+        {
+            if (osPlatform == null) throw new ArgumentNullException("name");
+            if (osPlatform.Length == 0) throw new ArgumentException(SR.Argument_EmptyValue, "name");
+            
+            _osPlatform = osPlatform;
+        }
+
+        public static OSPlatform Create(string osPlatform)
+        {
+            return new OSPlatform(osPlatform);
+        }
+
+        public bool Equals(OSPlatform other)
+        {
+            return string.Equals(other._osPlatform, _osPlatform, StringComparison.Ordinal);
+        }
+
+        public override bool Equals(object obj)
+        {
+            if (obj is OSPlatform)
+            {
+                return Equals((OSPlatform)obj);
+            }
+
+            return false;
+        }
+
+        public override int GetHashCode()
+        {
+            return _osPlatform == null ? 0 : _osPlatform.GetHashCode();
+        }
+
+        public override string ToString()
+        {
+            return _osPlatform ?? string.Empty;
+        }
+
+        public static bool operator ==(OSPlatform left, OSPlatform right)
+        {
+            return left.Equals(right);
+        }
+
+        public static bool operator !=(OSPlatform left, OSPlatform right)
+        {
+            return !(left == right);
+        }
+    }
+}

src/System.Runtime.Environment/System.Runtime.Environment.sln renamed to src/System.Runtime.InteropServices.RuntimeInformation/System.Runtime.InteropServices.RuntimeInformation.sln

@@ -5,9 +5,9 @@ namespace System.Runtime.InteropServices
 {
     public static class RuntimeInformation
     {
-        public static bool IsOperatingSystem(OSName osName)
+        public static bool IsOSPlatform(OSPlatform osPlatform)
         {
-            return OSName.Linux == osName;
+            return OSPlatform.Linux == osPlatform;
         }
     }
 }

src/System.Runtime.InteropServices.RuntimeInformation/src/OSPlatform.cs

@@ -5,9 +5,9 @@ namespace System.Runtime.InteropServices
 {
     public static class RuntimeInformation
     {
-        public static bool IsOperatingSystem(OSName osName)
+        public static bool IsOSPlatform(OSPlatform osPlatform)
         {
-            return OSName.OSX == osName;
+            return OSPlatform.OSX == osPlatform;
         }
     }
 }

src/System.Runtime.Environment/src/Resources/Strings.resx renamed to src/System.Runtime.InteropServices.RuntimeInformation/src/Resources/Strings.resx

@@ -5,9 +5,9 @@ namespace System.Runtime.InteropServices
 {
     public static class RuntimeInformation
     {
-        public static bool IsOperatingSystem(OSName osName)
+        public static bool IsOSPlatform(OSPlatform osPlatform)
         {
-            return OSName.Windows == osName;
+            return OSPlatform.Windows == osPlatform;
         }
     }
 }

src/System.Runtime.Environment/src/RuntimeInformation.Linux.cs renamed to src/System.Runtime.InteropServices.RuntimeInformation/src/RuntimeInformation.Linux.cs

@@ -6,7 +6,7 @@
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
     <OutputType>Library</OutputType>
     <RootNamespace>System.Runtime.InteropServices</RootNamespace>
-    <AssemblyName>System.Runtime.Environment</AssemblyName>
+    <AssemblyName>System.Runtime.InteropServices.RuntimeInformation</AssemblyName>
     <AssemblyVersion>4.0.0.0</AssemblyVersion>
     <ProjectGuid>{F9DF2357-81B4-4317-908E-512DA9395583}</ProjectGuid>
   </PropertyGroup>
@@ -30,7 +30,7 @@
     <None Include="project.json" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="OSName.cs" />
+    <Compile Include="OSPlatform.cs" />
   </ItemGroup>
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.targets))\dir.targets" />
 </Project>