<PackageReference Include="NUnit" Version="4.3.0" />

NUnit.Framework.Internal.StringTokenEnumerator

Allows enumerating sub-strings from a string based on separator char. Basically a less allocating version of string.Split.
namespace NUnit.Framework.Internal { internal struct StringTokenEnumerator : IEnumerator<string>, IEnumerator, IDisposable, IEnumerable { public string Current { get; } public StringTokenEnumerator(string target, char separator, bool returnEmptyTokens); public bool MoveNext(); public void Reset(); public void Dispose(); public StringTokenEnumerator GetEnumerator(); } }