NonParallelizableAttribute public sealed class NonParallelizableAttribute : ParallelizableAttribute Marks tests that should NOT be run in parallel. Documentation Code using System; namespace NUnit.Framework { [AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Method, AllowMultiple = false, Inherited = true)] public sealed class NonParallelizableAttribute : ParallelizableAttribute { public NonParallelizableAttribute() : base(ParallelScope.None) { } } }