Return workload manifests in defined, controllable order

src/Resolvers/Microsoft.NET.Sdk.WorkloadManifestReader/SdkDirectoryWorkloadManifestProvider.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
 using System.IO;
 using System.Linq;
 using Microsoft.DotNet.Cli;
@@ -17,7 +18,7 @@ public class SdkDirectoryWorkloadManifestProvider : IWorkloadManifestProvider
         private readonly string [] _manifestDirectories;
         private static HashSet<string> _outdatedManifestIds = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { "microsoft.net.workload.android", "microsoft.net.workload.blazorwebassembly", "microsoft.net.workload.ios",
             "microsoft.net.workload.maccatalyst", "microsoft.net.workload.macos", "microsoft.net.workload.tvos" };
-        private readonly HashSet<string>? _knownManifestIds;
+        private readonly Dictionary<string, int>? _knownManifestIdsAndOrder;
 
         public SdkDirectoryWorkloadManifestProvider(string sdkRootPath, string sdkVersion, string? userProfileDir)
             : this(sdkRootPath, sdkVersion, Environment.GetEnvironmentVariable, userProfileDir)
@@ -44,7 +45,12 @@ internal SdkDirectoryWorkloadManifestProvider(string sdkRootPath, string sdkVers
             var knownManifestIdsFilePath = Path.Combine(_sdkRootPath, "sdk", sdkVersion, "IncludedWorkloadManifests.txt");
             if (File.Exists(knownManifestIdsFilePath))
             {
-                _knownManifestIds = File.ReadAllLines(knownManifestIdsFilePath).Where(l => !string.IsNullOrEmpty(l)).ToHashSet();
+                _knownManifestIdsAndOrder = new Dictionary<string, int>();
+                int lineNumber = 0;
+                foreach (var manifestId in File.ReadAllLines(knownManifestIdsFilePath).Where(l => !string.IsNullOrEmpty(l)))
+                {
+                    _knownManifestIdsAndOrder[manifestId] = lineNumber++;
+                }
             }
 
             string? userManifestsDir = userProfileDir is null ? null : Path.Combine(userProfileDir, "sdk-manifests", _sdkVersionBand.ToString());
@@ -126,9 +132,9 @@ public IEnumerable<string> GetManifestDirectories()
                 }
             }
 
-            if (_knownManifestIds != null && _knownManifestIds.Any(id => !manifestIdsToDirectories.ContainsKey(id)))
+            if (_knownManifestIdsAndOrder != null && _knownManifestIdsAndOrder.Keys.Any(id => !manifestIdsToDirectories.ContainsKey(id)))
             {
-                var missingManifestIds = _knownManifestIds.Where(id => !manifestIdsToDirectories.ContainsKey(id));
+                var missingManifestIds = _knownManifestIdsAndOrder.Keys.Where(id => !manifestIdsToDirectories.ContainsKey(id));
                 foreach (var missingManifestId in missingManifestIds)
                 {
                     var manifestDir = FallbackForMissingManifest(missingManifestId);
@@ -139,7 +145,21 @@ public IEnumerable<string> GetManifestDirectories()
                 }
             }
 
-            return manifestIdsToDirectories.Values;
+            //  Return manifests in a stable order.  Manifests in the IncludedWorkloadManifests.txt file will be first, and in the same order they appear in that file.
+            //  Then the rest of the manifests (if any) will be returned in (ordinal case-insensitive) alphabetical order.
+            return manifestIdsToDirectories
+                .OrderBy(kvp =>
+                {
+                    if (_knownManifestIdsAndOrder != null &&
+                        _knownManifestIdsAndOrder.TryGetValue(kvp.Key, out var order))
+                    {
+                        return order;
+                    }
+                    return int.MaxValue;
+                })
+                .ThenBy(kvp => kvp.Key, StringComparer.OrdinalIgnoreCase)
+                .Select(kvp => kvp.Value)
+                .ToList();
         }
 
         private string FallbackForMissingManifest(string manifestId)

src/Tests/Microsoft.NET.Sdk.WorkloadManifestReader.Tests/SdkDirectoryWorkloadManifestProviderTests.cs

@@ -343,6 +343,43 @@ var sdkDirectoryWorkloadManifestProvider
                 .BeEquivalentTo("6.0.100-preview.4/iOS", "6.0.100/Android");
         }
 
+        [Fact]
+        public void ItReturnsManifestsInOrderFromIncludedWorkloadManifestsFile()
+        {
+            var testDirectory = _testAssetsManager.CreateTestDirectory().Path;
+            var fakeDotnetRootDirectory = Path.Combine(testDirectory, "dotnet");
+
+            //  microsoft.net.workload.mono.toolchain.net6, microsoft.net.workload.mono.toolchain.net7, microsoft.net.workload.emscripten.net6, microsoft.net.workload.emscripten.net7
+
+            var currentSdkVersion = "7.0.100";
+            var fallbackWorkloadBand = "7.0.100-rc.2";
+
+            CreateMockManifest(fakeDotnetRootDirectory, currentSdkVersion, "NotInIncudedWorkloadsFile");
+            CreateMockManifest(fakeDotnetRootDirectory, currentSdkVersion, "Microsoft.Net.Workload.Mono.Toolchain.net6");
+            CreateMockManifest(fakeDotnetRootDirectory, fallbackWorkloadBand, "Microsoft.Net.Workload.Mono.Toolchain.net7");
+            CreateMockManifest(fakeDotnetRootDirectory, fallbackWorkloadBand, "Microsoft.Net.Workload.Emscripten.net6");
+            CreateMockManifest(fakeDotnetRootDirectory, currentSdkVersion, "Microsoft.Net.Workload.Emscripten.net7");
+
+            var knownWorkloadsFilePath = Path.Combine(fakeDotnetRootDirectory, "sdk", currentSdkVersion, "IncludedWorkloadManifests.txt");
+            Directory.CreateDirectory(Path.GetDirectoryName(knownWorkloadsFilePath)!);
+            File.WriteAllText(knownWorkloadsFilePath, @"
+Microsoft.Net.Workload.Mono.Toolchain.net6
+Microsoft.Net.Workload.Mono.Toolchain.net7
+Microsoft.Net.Workload.Emscripten.net6
+Microsoft.Net.Workload.Emscripten.net7"
+                .Trim());
+
+            var sdkDirectoryWorkloadManifestProvider = new SdkDirectoryWorkloadManifestProvider(sdkRootPath: fakeDotnetRootDirectory, sdkVersion: currentSdkVersion, userProfileDir: null);
+
+            GetManifestContents(sdkDirectoryWorkloadManifestProvider)
+                .Should()
+                .Equal($"{currentSdkVersion}/Microsoft.Net.Workload.Mono.Toolchain.net6",
+                       $"{fallbackWorkloadBand}/Microsoft.Net.Workload.Mono.Toolchain.net7",
+                       $"{fallbackWorkloadBand}/Microsoft.Net.Workload.Emscripten.net6",
+                       $"{currentSdkVersion}/Microsoft.Net.Workload.Emscripten.net7",
+                       $"{currentSdkVersion}/NotInIncudedWorkloadsFile");
+        }
+
         private void CreateMockManifest(string rootDir, string version, string manifestId)
         {
             var manifestDirectory = Path.Combine(rootDir, "sdk-manifests", version);