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Resolve the object-model assembly by name in AppDomain wiring (Phase 6e-4b) #9628

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Merged
Evangelink merged 1 commit into from
Jul 5, 2026
Merged

Resolve the object-model assembly by name in AppDomain wiring (Phase 6e-4b) #9628

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22 changes: 17 additions & 5 deletions src/Adapter/MSTestAdapter.PlatformServices/Utilities/AppDomainUtilities.cs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,11 @@
// Copyright (c) Microsoft Corporation. All rights reserved.
// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

#if NETFRAMEWORK

using Microsoft.VisualStudio.TestPlatform.MSTest.TestAdapter;
using Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.Deployment;
using Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.Interface;
using Microsoft.VisualStudio.TestPlatform.ObjectModel;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace Microsoft.VisualStudio.TestPlatform.MSTestAdapter.PlatformServices.Utilities;
Expand All @@ -18,9 +17,22 @@ internal static class AppDomainUtilities
{
private const string ObjectModelVersionBuiltAgainst = "11.0.0.0";

private const string ObjectModelAssemblyName = "Microsoft.VisualStudio.TestPlatform.ObjectModel";

private static readonly Version DefaultVersion = new();
private static readonly Version Version45 = new("4.5");

/// <summary>
/// Resolves the loaded VSTest object-model assembly by simple name, so this AppDomain-wiring code does not
/// need a compile-time reference to it. By the time these methods run (test source host setup during
/// discovery/execution) the adapter has already loaded the object model into the current (parent) domain,
/// so its identity — including any binding redirect in effect — matches what a direct type reference resolved to.
/// </summary>
/// <returns>The object-model assembly.</returns>
private static Assembly GetObjectModelAssembly()
=> AppDomain.CurrentDomain.GetAssemblies().FirstOrDefault(a => string.Equals(a.GetName().Name, ObjectModelAssemblyName, StringComparison.Ordinal))
?? Assembly.Load(ObjectModelAssemblyName);

/// <summary>
/// Gets or sets the Xml Utilities instance.
/// </summary>
Expand Down Expand Up @@ -90,7 +102,7 @@ internal static string GetTargetFrameworkVersionString(string testSourcePath)

var resolutionPaths = new List<string>
{
Path.GetDirectoryName(typeof(TestCase).Assembly.Location),
Path.GetDirectoryName(GetObjectModelAssembly().Location),
Path.GetDirectoryName(testSourcePath),
};

Expand Down Expand Up @@ -157,10 +169,10 @@ internal static void SetConfigurationFile(AppDomainSetup appDomainSetup, string?
try
{
// Add redirection of the built 11.0 Object Model assembly to the current version if that is not 11.0
string currentVersionOfObjectModel = typeof(TestCase).Assembly.GetName().Version.ToString();
string currentVersionOfObjectModel = GetObjectModelAssembly().GetName().Version.ToString();
if (!string.Equals(currentVersionOfObjectModel, ObjectModelVersionBuiltAgainst, StringComparison.Ordinal))
{
AssemblyName assemblyName = typeof(TestCase).Assembly.GetName();
AssemblyName assemblyName = GetObjectModelAssembly().GetName();
Comment on lines +172 to +175

@github-actions github-actions Bot Jul 5, 2026

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[NIT] Performance / Code Structure

GetObjectModelAssembly() is called twice within the same try-block. Unlike the old typeof(TestCase).Assembly (a JIT-inlined runtime constant), each call to GetObjectModelAssembly() allocates a LINQ query over AppDomain.CurrentDomain.GetAssemblies(). The practical cost is negligible in a setup path, but the logic can be simplified to a single call:

// Capture once — avoids two linear scans of GetAssemblies()
AssemblyName assemblyName = GetObjectModelAssembly().GetName();
string currentVersionOfObjectModel = assemblyName.Version!.ToString();
if (!string.Equals(currentVersionOfObjectModel, ObjectModelVersionBuiltAgainst, StringComparison.Ordinal))
{
    byte[] configurationBytes =
        XmlUtilities.AddAssemblyRedirection(
            testSourceConfigFile,
            assemblyName,
            ObjectModelVersionBuiltAgainst,
            assemblyName.Version!.ToString());
    appDomainSetup.SetConfigurationBytes(configurationBytes);
}

This also surfaces the Version! null-annotation more explicitly — AssemblyName.Version is nullable, though it will never be null for the VSTest ObjectModel in practice.

byte[] configurationBytes =
XmlUtilities.AddAssemblyRedirection(
testSourceConfigFile,
Expand Down
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