ArchUnitNET-mscorlib-problem

• Using Visual Studio 2026 18.10.1 and its Test Explorer.
• All projects are .NET Framework 4.8 projects with SDK style.
• Test projects use:
  • MSTest 4.4.1
  • TngTech.ArchUnitNET.MSTestV4 0.13.4
• Project ProjectA has a single class ClassA.
• Project TestsA references ProjectA and its test calls ArchLoader.Build() with no problem.
• Project ProjectB references ProjectA and has a single class ClassB that uses ClassA
• Project TestsB references ProjectB and its test calls ArchLoader.Build() causing exception:

Message: 

Test method TestsB.Tests.TestB threw exception:
Mono.Cecil.AssemblyResolutionException: Failed to resolve assembly: 'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'

Stack Trace: 

BaseAssemblyResolver.Resolve(AssemblyNameReference name, ReaderParameters parameters)
DefaultAssemblyResolver.Resolve(AssemblyNameReference name)
MetadataResolver.Resolve(TypeReference type)
TypeReference.Resolve()
MonoCecilTypeExtensions.IsAttribute(TypeDefinition typeDefinition)
DomainResolver.GetOrCreateTypeInstanceFromTypeDefinition(TypeDefinition typeDefinition, Boolean isStub)
DomainResolver.GetOrCreateFieldMember(IType type, FieldReference fieldReference)
WhereSelectEnumerableIterator`2.MoveNext()
<ConcatIterator>d__59`1.MoveNext()
<ConcatIterator>d__59`1.MoveNext()
WhereEnumerableIterator`1.MoveNext()
EnumerableExtensions.ForEach[T](IEnumerable`1 source, Action`1[] actions)
TypeProcessor.AddMembers(ITypeInstance`1 typeInstance, TypeDefinition typeDefinition, DomainResolver domainResolver)
ArchBuilder.<ProcessTypes>b__9_0(ValueTuple`2 entry)
<>c__DisplayClass7_0`3.<CombineSelectors>b__0(TSource x)
WhereSelectEnumerableIterator`2.MoveNext()
List`1.InsertRange(Int32 index, IEnumerable`1 collection)
ArchBuilder.ProcessTypes()
ArchBuilder.Build(Boolean skipRuleEvaluationCache, Boolean skipArchitectureCache)
ArchLoader.Build()
Tests.TestB() line 16