Support reading package folder locations out of the lock file

The task previously was constructing the path to the user's packages
location itself, which had various issues. It meant that if the restore
was done with a different path, we don't know that. It also meant we
didn't handle the paths specified in nuget.config. Now, if the paths
are present in the lock file, we'll use that. Otherwise, we'll construct
our old path as before. Any explicitly given path to the task is
still used no matter what.

src/Microsoft.NuGet.Build.Tasks.Tests/Json/Json.resx

@@ -139,4 +139,7 @@
   <data name="nativeWinMD" type="System.Resources.ResXFileRef, System.Windows.Forms">
     <value>nativeWinMD.json;System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089;utf-8</value>
   </data>
+  <data name="LockFileWithWithSpecifiedPackageFolders" type="System.Resources.ResXFileRef, System.Windows.Forms">
+    <value>lockfilewithwithspecifiedpackagefolders.json;System.String, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089;utf-8</value>
+  </data>
 </root>

src/Microsoft.NuGet.Build.Tasks.Tests/Json/LockFileWithWithSpecifiedPackageFolders.json

@@ -0,0 +1,52 @@
+{
+  "locked": false,
+  "version": 2,
+  "targets": {
+    ".NETFramework,Version=v4.5": {
+      "Newtonsoft.Json/8.0.3": {
+        "type": "package",
+        "compile": {
+          "lib/net45/Newtonsoft.Json.dll": {}
+        },
+        "runtime": {
+          "lib/net45/Newtonsoft.Json.dll": {}
+        }
+      }
+    }
+  },
+  "libraries": {
+    "Newtonsoft.Json/8.0.3": {
+      "sha512": "KGsYQdS2zLH+H8x2cZaSI7e+YZ4SFIbyy1YJQYl6GYBWjf5o4H1A68nxyq+WTyVSOJQ4GqS/DiPE+UseUizgMg==",
+      "type": "package",
+      "path": "newtonsoft.json/8.0.3",
+      "files": [
+        "lib/net20/Newtonsoft.Json.dll",
+        "lib/net20/Newtonsoft.Json.xml",
+        "lib/net35/Newtonsoft.Json.dll",
+        "lib/net35/Newtonsoft.Json.xml",
+        "lib/net40/Newtonsoft.Json.dll",
+        "lib/net40/Newtonsoft.Json.xml",
+        "lib/net45/Newtonsoft.Json.dll",
+        "lib/net45/Newtonsoft.Json.xml",
+        "lib/portable-net40+sl5+wp80+win8+wpa81/Newtonsoft.Json.dll",
+        "lib/portable-net40+sl5+wp80+win8+wpa81/Newtonsoft.Json.xml",
+        "lib/portable-net45+wp80+win8+wpa81+dnxcore50/Newtonsoft.Json.dll",
+        "lib/portable-net45+wp80+win8+wpa81+dnxcore50/Newtonsoft.Json.xml",
+        "newtonsoft.json.8.0.3.nupkg.sha512",
+        "newtonsoft.json.nuspec",
+        "tools/install.ps1"
+      ]
+    }
+  },
+  "projectFileDependencyGroups": {
+    "": [
+      "Newtonsoft.Json"
+    ],
+    ".NETFramework,Version=v4.5": []
+  },
+  "tools": {},
+  "projectFileToolGroups": {},
+  "packageFolders": {
+    "C:\\PackageFolder\\": {}
+  }
+}

src/Microsoft.NuGet.Build.Tasks.Tests/Microsoft.NuGet.Build.Tasks.Tests.csproj

@@ -55,6 +55,7 @@
       <DependentUpon>Json.resx</DependentUpon>
     </Compile>
     <Compile Include="NuGetTestHelpers.cs" />
+    <Compile Include="PackageFolderTests.cs" />
     <Compile Include="PreprocessorTests.cs" />
     <Compile Include="ProjectReferences\ProjectReferenceTests.cs" />
     <Compile Include="ProjectReferences\Resources.Designer.cs">
@@ -78,6 +79,7 @@
     <None Include="Json\FluentAssertions.lock.json" />
     <None Include="Json\FluentAssertionsAndWin10.lock.json" />
     <None Include="Json\nativeWinMD.json" />
+    <None Include="Json\LockFileWithWithSpecifiedPackageFolders.json" />
     <None Include="Json\Win10.Edm.json" />
     <None Include="Json\Win10.json" />
     <None Include="Json\Win10.xunit.json" />

src/Microsoft.NuGet.Build.Tasks.Tests/NuGetTestHelpers.cs

@@ -26,13 +26,13 @@ public static ResolvePackagesResult ResolvePackagesWithJsonFileContents(
             TryGetRuntimeVersion tryGetRuntimeVersion = null,
             bool includeFrameworkReferences = true,
             string projectJsonFileContents = null,
-            IEnumerable<ITaskItem> projectReferencesCreatingPackages = null)
+            IEnumerable<ITaskItem> projectReferencesCreatingPackages = null,
+            bool createTemporaryFolderForPackages = true)
         {
             var rootDirectory = new TempRoot();
             using (rootDirectory)
             {
                 var projectDirectory = rootDirectory.CreateDirectory();
-                var packagesDirectory = rootDirectory.CreateDirectory();
 
                 var projectLockJsonFile = projectDirectory.CreateFile("project.lock.json");
                 projectLockJsonFile.WriteAllText(projectLockJsonFileContents);
@@ -43,21 +43,31 @@ public static ResolvePackagesResult ResolvePackagesWithJsonFileContents(
                     projectJsonFile.WriteAllText(projectJsonFileContents);
                 }
 
-                var filesInPackages = new HashSet<string>(
-                    GetFakeFileNamesFromPackages(projectLockJsonFileContents, packagesDirectory.Path),
-                    StringComparer.OrdinalIgnoreCase);
+                var filesInPackages = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+                DisposableDirectory packagesDirectory = null;
+
+                if (createTemporaryFolderForPackages)
+                {
+                    packagesDirectory = rootDirectory.CreateDirectory();
+
+                    foreach (var fileInPackage in GetFakeFileNamesFromPackages(projectLockJsonFileContents, packagesDirectory.Path))
+                    {
+                        filesInPackages.Add(fileInPackage);
+                    }
+                }
 
                 // Don't require the packages be restored on the machine
-                DirectoryExists directoryExists = path => path.StartsWith(packagesDirectory.Path) || Directory.Exists(path);
+                ResolveNuGetPackageAssets task = null;
+                DirectoryExists directoryExists = path => task.GetPackageFolders().Any(l => path.StartsWith(l)) || Directory.Exists(path);
                 FileExists fileExists = path => filesInPackages.Contains(path) || File.Exists(path);
 
-                ResolveNuGetPackageAssets task = new ResolveNuGetPackageAssets(directoryExists, fileExists, tryGetRuntimeVersion);
+                task = new ResolveNuGetPackageAssets(directoryExists, fileExists, tryGetRuntimeVersion);
                 var sw = new StringWriter();
                 task.BuildEngine = new MockBuildEngine(sw);
 
                 task.AllowFallbackOnTargetSelection = allowFallbackOnTargetSelection;
                 task.IncludeFrameworkReferences = includeFrameworkReferences;
-                task.NuGetPackagesDirectory = packagesDirectory.Path;
+                task.NuGetPackagesDirectory = packagesDirectory?.Path;
                 task.RuntimeIdentifier = runtimeIdentifier;
                 task.ProjectReferencesCreatingPackages = (projectReferencesCreatingPackages ?? Enumerable.Empty<ITaskItem>()).ToArray();
                 task.ProjectLockFile = projectLockJsonFile.Path;

src/Microsoft.NuGet.Build.Tasks.Tests/PackageFolderTests.cs

@@ -0,0 +1,24 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.NuGet.Build.Tasks.Tests
+{
+    public class PackageFolderTests
+    {
+        [Fact]
+        public void ResolveWithLockFileWithPackageFolders()
+        {
+            var result = NuGetTestHelpers.ResolvePackagesWithJsonFileContents(
+                Json.Json.LockFileWithWithSpecifiedPackageFolders,
+                ".NETFramework,Version=v4.5",
+                runtimeIdentifier: null,
+                createTemporaryFolderForPackages: false);
+
+            Assert.Equal(@"C:\PackageFolder\Newtonsoft.Json\8.0.3\lib\net45\Newtonsoft.Json.dll", result.References.Single().ItemSpec);
+        }
+    }
+}

src/Microsoft.NuGet.Build.Tasks/ResolveNuGetPackageAssets.cs

@@ -44,6 +44,8 @@ public sealed class ResolveNuGetPackageAssets : Task
         private readonly List<ITaskItem> _contentItems = new List<ITaskItem>();
         private readonly List<ITaskItem> _fileWrites = new List<ITaskItem>();
 
+        private readonly List<string> _packageFolders = new List<string>();
+
         private readonly Dictionary<string, string> _projectReferencesToOutputBasePaths = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
 
         #region UnitTestSupport
@@ -72,6 +74,13 @@ internal ResolveNuGetPackageAssets(DirectoryExists directoryExists, FileExists f
 
             _reportExceptionsToMSBuildLogger = false;
         }
+
+        // For unit testing.
+        internal IEnumerable<string> GetPackageFolders()
+        {
+            return _packageFolders;
+        }
+
         #endregion
 
         /// <summary>
@@ -233,6 +242,8 @@ private void ExecuteCore()
                 lockFile = JObject.Load(new JsonTextReader(streamReader));
             }
 
+            PopulatePackageFolders(lockFile);
+
             PopulateProjectReferenceMaps();
             GetReferences(lockFile);
             GetCopyLocalItems(lockFile);
@@ -241,6 +252,41 @@ private void ExecuteCore()
             ProduceContentAssets(lockFile);
         }
 
+        private void PopulatePackageFolders(JObject lockFile)
+        {
+            // If we explicitly were given a path, let's use that
+            if (!string.IsNullOrEmpty(NuGetPackagesDirectory))
+            {
+                _packageFolders.Add(NuGetPackagesDirectory);
+            }
+
+            // Newer versions of NuGet can now specify the final list of locations in the lock file
+            var packageFolders = lockFile["packageFolders"] as JObject;
+
+            if (packageFolders != null)
+            {
+                foreach (var packageFolder in packageFolders.Properties())
+                {
+                    _packageFolders.Add(packageFolder.Name);
+                }
+            }
+
+            // If we didn't have any folders, let's fall back to the environment variable or user profile
+            if (_packageFolders.Count == 0)
+            {
+                string packagesFolder = Environment.GetEnvironmentVariable("NUGET_PACKAGES");
+
+                if (!string.IsNullOrEmpty(packagesFolder))
+                {
+                    _packageFolders.Add(packagesFolder);
+                }
+                else
+                {
+                    _packageFolders.Add(Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".nuget", "packages"));
+                }
+            }
+        }
+
         private void PopulateProjectReferenceMaps()
         {
             foreach (var projectReference in ProjectReferencesCreatingPackages ?? new ITaskItem[] { })
@@ -579,7 +625,7 @@ private static string GetNuGetLanguageName(string projectLanguage)
         private void ProduceContentAsset(NuGetPackageObject package, JProperty sharedAsset, IReadOnlyDictionary<string, string> preprocessorValues, string preprocessedOutputDirectory)
         {
             string pathToFinalAsset = package.GetFullPathToFile(sharedAsset.Name);
-            
+
             if (sharedAsset.Value["ppOutputPath"] != null)
             {
                 if (preprocessedOutputDirectory == null)
@@ -775,7 +821,7 @@ private IEnumerable<ITaskItem> CreateItems(NuGetPackageObject package, string ke
                 {
                     targetPath = Path.Combine(culture, Path.GetFileName(file.Name));
                 }
-                
+
                 var item = CreateItem(package, package.GetFullPathToFile(file.Name), targetPath);
 
                 item.SetMetadata("Private", "false");
@@ -844,32 +890,17 @@ private void GetReferencedPackages(JObject lockFile)
 
         private string GetNuGetPackagePath(string packageId, string packageVersion)
         {
-            string packagesFolder = GetNuGetPackagesPath();
-            string packagePath = Path.Combine(packagesFolder, packageId, packageVersion);
-
-            if (!_directoryExists(packagePath))
+            foreach (var packagesFolder in _packageFolders)
             {
-                throw new ExceptionFromResource(nameof(Strings.PackageFolderNotFound), packageId, packageVersion, packagesFolder);
-            }
-
-            return packagePath;
-        }
+                string packagePath = Path.Combine(packagesFolder, packageId, packageVersion);
 
-        private string GetNuGetPackagesPath()
-        {
-            if (!string.IsNullOrEmpty(NuGetPackagesDirectory))
-            {
-                return NuGetPackagesDirectory;
-            }
-
-            string packagesFolder = Environment.GetEnvironmentVariable("NUGET_PACKAGES");
-
-            if (!string.IsNullOrEmpty(packagesFolder))
-            {
-                return packagesFolder;
+                if (_directoryExists(packagePath))
+                {
+                    return packagePath;
+                }
             }
 
-            return Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".nuget", "packages");
+            throw new ExceptionFromResource(nameof(Strings.PackageFolderNotFound), packageId, packageVersion, string.Join(", ", _packageFolders));
         }
 
         private IEnumerable<NuGetPackageObject> GetPackagesFromTarget(JObject lockFile, JObject target)
@@ -915,7 +946,7 @@ private IEnumerable<NuGetPackageObject> GetPackagesFromTarget(JObject lockFile,
                     };
                 }
                 else
-                { 
+                {
                     fullPackagePathGenerator = () => GetNuGetPackagePath(id, version);
                 }