InvokeUtil.Exec snapshots CompilerLoadContext.Assemblies before running the test, then asserts the set is unchanged afterward. AssertEx has static fields that lazily initialize DiffPlex on first use; when that first use fell between the snapshot and the final comparison, DiffPlex (and Microsoft.Win32.Registry as a netstandard2.0 compat shim on .NET 10) appeared only in the post-test list, failing the SetEqual check. Only LoadStream was affected because the other variants ran in process contexts where a prior test had already triggered AssertEx initialization.

Changes

• InvokeUtil.cs: Call RuntimeHelpers.RunClassConstructor(typeof(AssertEx).TypeHandle) before taking the compilerContextAssemblies snapshot, ensuring DiffPlex and any compat-shim assemblies it pulls in are already present in both sides of the comparison.

// Before (snapshot taken before AssertEx/DiffPlex are initialized)
var loader = new AnalyzerAssemblyLoader(...);
var compilerContextAssemblies = loader.CompilerLoadContext.Assemblies.SelectAsArray(...);

// After (force initialization first so the snapshot includes infrastructure assemblies)
var loader = new AnalyzerAssemblyLoader(...);
RuntimeHelpers.RunClassConstructor(typeof(AssertEx).TypeHandle);
var compilerContextAssemblies = loader.CompilerLoadContext.Assemblies.SelectAsArray(...);

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