Code analyzer preventing test assemblies from being referenced

UnitTestAssembliesMustNotBeReferenced.cs

[DiagnosticAnalyzer(LanguageNames.CSharp)]
public class UnitTestAssembliesMustNotBeReferenced : DiagnosticAnalyzer
{
    public const string DiagnosticId = "Architecture";

    private static DiagnosticDescriptor Descriptor { get; } =
        new DiagnosticDescriptor("AR0001", 
            "UnitTest assemblies must not be referenced by other assemblies",
            "The assembly '{0}' references the unit test assembly: {1}",
            category: "Architecture",
            defaultSeverity: DiagnosticSeverity.Error,
            isEnabledByDefault: true);

    public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics =>
        ImmutableArray.Create(Descriptor);

    public override void Initialize(AnalysisContext context)
    {
        context.EnableConcurrentExecution();
        context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
        context.RegisterCompilationAction(AnalyzeCompilation);
    }

    private void AnalyzeCompilation(CompilationAnalysisContext context)
    {
        foreach (var item in context.Compilation.References)
        {
            if (Path.GetFileNameWithoutExtension(item.Display)
              .EndsWith(".UnitTests", StringComparison.OrdinalIgnoreCase))
            {
                context.ReportDiagnostic(
                  Diagnostic.Create(
                      Descriptor,
                      null,
                      context.Compilation.AssemblyName,
                      Path.GetFileNameWithoutExtension(item.Display)));
            }
        }
    }
}