Implement reftable reference resolution (#1498)

* Implement support for reftable

* Fix GitVariableName hashing

Author: tmat

eng/Version.Details.props

@@ -8,6 +8,7 @@ This file should be imported by eng/Versions.props
     <!-- dotnet/dotnet dependencies -->
     <MicrosoftDotNetArcadeSdkPackageVersion>10.0.0-beta.25506.103</MicrosoftDotNetArcadeSdkPackageVersion>
     <SystemCommandLinePackageVersion>2.0.0</SystemCommandLinePackageVersion>
+    <SystemIOHashingPackageVersion>10.0.0-rc.2.25502.107</SystemIOHashingPackageVersion>
     <!-- dotnet/msbuild dependencies -->
     <MicrosoftBuildPackageVersion>17.11.31</MicrosoftBuildPackageVersion>
     <MicrosoftBuildTasksCorePackageVersion>17.11.31</MicrosoftBuildTasksCorePackageVersion>

eng/Version.Details.xml

@@ -21,5 +21,9 @@
       <Uri>https://github.com/dotnet/msbuild</Uri>
       <Sha>933b72e36e86c22ba73e8b8148488f8298bb73c7</Sha>
     </Dependency>
+    <Dependency Name="System.IO.Hashing" Version="10.0.0-rc.2.25502.107">
+    <Uri>https://github.com/dotnet/dotnet</Uri>
+    <Sha>be28ec777bf12db631725399c442448d52093087</Sha>
+    </Dependency>
   </ToolsetDependencies>
 </Dependencies>

src/Directory.Packages.props

@@ -22,6 +22,7 @@
 
     <!-- Runtime dependencies -->
     <PackageVersion Include="System.Text.Json" Version="$(SystemTextJsonVersion)" />
+    <PackageVersion Include="System.IO.Hashing" Version="$(SystemIOHashingPackageVersion)" />
   </ItemGroup>
 
   <!-- External dependencies -->

src/Microsoft.Build.Tasks.Git.UnitTests/GitConfigTests.cs

@@ -1,8 +1,10 @@
 // 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.txt file in the project root for more information.
+
 using System;
 using System.Collections.Generic;
+using System.Collections.Immutable;
 using System.IO;
 using System.Linq;
 using System.Text;
@@ -448,5 +450,30 @@ public void TryParseBooleanValue_Error(string? str)
         {
             Assert.False(GitConfig.TryParseBooleanValue(str, out _));
         }
+
+        [Theory]
+        [InlineData(null, ReferenceStorageFormat.LooseFiles)]
+        [InlineData("reftable", ReferenceStorageFormat.RefTable)]
+        internal void RefStorage(string? value, ReferenceStorageFormat expected)
+        {
+            var variables = ImmutableDictionary<GitVariableName, ImmutableArray<string>>.Empty;
+            if (value != null)
+            {
+                variables = variables.Add(new GitVariableName("extensions", "", "refStorage"), [value]);
+            }
+
+            Assert.Equal(expected, new GitConfig(variables).ReferenceStorageFormat);
+        }
+
+        [Theory]
+        [InlineData("")]
+        [InlineData("x")]
+        [InlineData("refTable")]
+        public void RefStorage_Invalid(string value)
+        {
+            Assert.Throws<InvalidDataException>(() =>
+                new GitConfig(ImmutableDictionary<GitVariableName, ImmutableArray<string>>.Empty
+                    .Add(new GitVariableName("extensions", "", "refStorage"), [value])));
+        }
     }
 }