How to return the lists of public and obsolete classes for specified .NET assembly?

Question

The function should return a list of public but obsolete classes

public static IEnumerable<string> GetPublicObsoleteClasses(string assemblyName)
        {
            return Assembly.ReflectionOnlyLoad(assemblyName).GetTypes()
                .Where(x => x.IsClass &&
                            x.IsPublic &&
                            Attribute.GetCustomAttributes(x)
                                .Any(y => y is ObsoleteAttribute))
                .Select(x => x.Name);
        }

However, it shows that ReflectionOnly loading is not supported on this platform.

There is a Unit Test for this method and it is not allowed to change it

[Test ]
         
        public void GetPublicObsoleteClassesShouldReturnRightList()
        {
            var expected = "CaseInsensitiveHashCodeProvider, ContractHelper, ExecutionEngineException, "+
                           "FirstMatchCodeGroup, IDispatchImplAttribute, PermissionRequestEvidence, "+
                           "SecurityTreatAsSafeAttribute, SetWin32ContextInIDispatchAttribute, "+
                           "UnionCodeGroup, UnmanagedMarshal";

            var obsoleteMembers = CommonTasks.GetPublicObsoleteClasses("mscorlib, Version=4.0.0.0").OrderBy(x=>x);
            var actual = string.Join(", ", obsoleteMembers);
            Assert.AreEqual(expected, actual);
        }

Answer 1

Since you are already referencing mscorlib and it is already loaded to run .NET, one option is to use a Type rather than a string to determine what assembly to use.

[Test]

public void GetPublicObsoleteClassesShouldReturnRightList()
{
    var expected = "CaseInsensitiveHashCodeProvider, ContractHelper, ExecutionEngineException, " +
                   "FirstMatchCodeGroup, IDispatchImplAttribute, PermissionRequestEvidence, " +
                   "SecurityTreatAsSafeAttribute, SetWin32ContextInIDispatchAttribute, " +
                   "UnionCodeGroup, UnmanagedMarshal";

    var obsoleteMembers = CommonTasks.GetPublicObsoleteClasses(typeof(string) /* mscorlib */).OrderBy(x => x);
    var actual = string.Join(", ", obsoleteMembers);
    Assert.AreEqual(expected, actual);
}

public static IEnumerable<string> GetPublicObsoleteClasses(Type typeFromAssembly)
{
    return typeFromAssembly.Assembly.GetTypes()
        .Where(x => x.IsClass &&
                    x.IsPublic &&
                    Attribute.GetCustomAttributes(x)
                        .Any(y => y is ObsoleteAttribute))
        .Select(x => x.Name);
}