AssertionException public class AssertionException : ResultStateException Thrown when an assertion failed. Documentation Code using NUnit.Framework.Interfaces; using System; using System.Runtime.CompilerServices; namespace NUnit.Framework { [Serializable] [NullableContext(1)] [Nullable(0)] public class AssertionException : ResultStateException { public override ResultState ResultState => ResultState.Failure; public AssertionException(string message) : base(message) { } public AssertionException(string message, [Nullable(2)] Exception inner) : base(message, inner) { } } }