<PackageReference Include="NUnit" Version="3.8.1" />

Check

static class Check
namespace System.Linq { internal static class Check { public static void Source(object source) { if (source == null) throw new ArgumentNullException("source"); } public static void Source1AndSource2(object source1, object source2) { if (source1 == null) throw new ArgumentNullException("source1"); if (source2 == null) throw new ArgumentNullException("source2"); } public static void SourceAndFuncAndSelector(object source, object func, object selector) { if (source == null) throw new ArgumentNullException("source"); if (func == null) throw new ArgumentNullException("func"); if (selector == null) throw new ArgumentNullException("selector"); } public static void SourceAndFunc(object source, object func) { if (source == null) throw new ArgumentNullException("source"); if (func == null) throw new ArgumentNullException("func"); } public static void SourceAndSelector(object source, object selector) { if (source == null) throw new ArgumentNullException("source"); if (selector == null) throw new ArgumentNullException("selector"); } public static void SourceAndPredicate(object source, object predicate) { if (source == null) throw new ArgumentNullException("source"); if (predicate == null) throw new ArgumentNullException("predicate"); } public static void FirstAndSecond(object first, object second) { if (first == null) throw new ArgumentNullException("first"); if (second == null) throw new ArgumentNullException("second"); } public static void SourceAndKeySelector(object source, object keySelector) { if (source == null) throw new ArgumentNullException("source"); if (keySelector == null) throw new ArgumentNullException("keySelector"); } public static void SourceAndKeyElementSelectors(object source, object keySelector, object elementSelector) { if (source == null) throw new ArgumentNullException("source"); if (keySelector == null) throw new ArgumentNullException("keySelector"); if (elementSelector == null) throw new ArgumentNullException("elementSelector"); } public static void SourceAndKeyResultSelectors(object source, object keySelector, object resultSelector) { if (source == null) throw new ArgumentNullException("source"); if (keySelector == null) throw new ArgumentNullException("keySelector"); if (resultSelector == null) throw new ArgumentNullException("resultSelector"); } public static void SourceAndCollectionSelectorAndResultSelector(object source, object collectionSelector, object resultSelector) { if (source == null) throw new ArgumentNullException("source"); if (collectionSelector == null) throw new ArgumentNullException("collectionSelector"); if (resultSelector == null) throw new ArgumentNullException("resultSelector"); } public static void SourceAndCollectionSelectors(object source, object collectionSelector, object selector) { if (source == null) throw new ArgumentNullException("source"); if (collectionSelector == null) throw new ArgumentNullException("collectionSelector"); if (selector == null) throw new ArgumentNullException("selector"); } public static void JoinSelectors(object outer, object inner, object outerKeySelector, object innerKeySelector, object resultSelector) { if (outer == null) throw new ArgumentNullException("outer"); if (inner == null) throw new ArgumentNullException("inner"); if (outerKeySelector == null) throw new ArgumentNullException("outerKeySelector"); if (innerKeySelector == null) throw new ArgumentNullException("innerKeySelector"); if (resultSelector == null) throw new ArgumentNullException("resultSelector"); } public static void GroupBySelectors(object source, object keySelector, object elementSelector, object resultSelector) { if (source == null) throw new ArgumentNullException("source"); if (keySelector == null) throw new ArgumentNullException("keySelector"); if (elementSelector == null) throw new ArgumentNullException("elementSelector"); if (resultSelector == null) throw new ArgumentNullException("resultSelector"); } } }