Expose GC.GetAllocatedBytesForCurrentThread in netcoreapp1.1

src/System.Runtime/ref/System.Runtime.cs

@@ -1152,6 +1152,9 @@ public static void RemoveMemoryPressure(long bytesAllocated) { }
         public static void ReRegisterForFinalize(object obj) { }
         public static void SuppressFinalize(object obj) { }
         public static void WaitForPendingFinalizers() { }
+#if netcoreapp11
+        public static long GetAllocatedBytesForCurrentThread() { return default(long); }
+#endif
     }
     public enum GCCollectionMode
     {

src/System.Runtime/tests/System.Runtime.Tests.csproj

@@ -103,6 +103,7 @@
   <ItemGroup Condition="'$(TargetGroup)' == 'netcoreapp1.1'">
     <Compile Include="System\ArrayTests.netcoreapp1.1.cs" />
     <Compile Include="System\EnumTests.netcoreapp1.1.cs" />
+    <Compile Include="System\GCTests.netcoreapp1.1.cs" />
     <Compile Include="System\IntPtrTests.netcoreapp1.1.cs" />
     <Compile Include="System\LazyTests.netcoreapp1.1.cs" />
     <Compile Include="System\Runtime\CompilerServices\RuntimeHelpersTests.netcoreapp1.1.cs" />

src/System.Runtime/tests/System/GCTests.cs

@@ -8,7 +8,7 @@
 
 namespace System.Tests
 {
-    public static class GCTests
+    public static partial class GCTests
     {
         private static bool s_is32Bits = IntPtr.Size == 4; // Skip IntPtr tests on 32-bit platforms
 

src/System.Runtime/tests/System/GCTests.netcoreapp1.1.cs

@@ -0,0 +1,27 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System;
+using Xunit;
+
+namespace System.Tests
+{
+    public static partial class GCTests
+    {
+        [Theory]
+        [InlineData(1000)]
+        [InlineData(100000)]
+        public static void GetAllocatedBytesForCurrentThread(int size)
+        {
+            long start = GC.GetAllocatedBytesForCurrentThread();
+
+            GC.KeepAlive(new String('a', size));
+
+            long end = GC.GetAllocatedBytesForCurrentThread();
+
+            Assert.True((end - start) > size, $"Allocated too little: start: {start} end: {end} size: {size}");
+            Assert.True((end - start) < 5 * size, $"Allocated too much: start: {start} end: {end} size: {size}");
+        }
+    }
+}