empty if null extension for readonly collections

src/EnumerablePlus/LinqEnumerablePlus.cs

@@ -154,8 +154,8 @@ public static void ForEach<T>(this IEnumerable<T> source, Action<T, int> action)
         var rnd = random ?? Random.Shared;
         return source switch
         {
-            IReadOnlyCollection<T> { Count: 0 } => default,
-            IReadOnlyList<T> { Count: > 0 } list => list[rnd.Next(list.Count)],
+            IReadOnlyCollection<T> {Count: 0} => default,
+            IReadOnlyList<T> {Count: > 0} list => list[rnd.Next(list.Count)],
             _ => source.Shuffle(rnd).FirstOrDefault(defaultValue),
         };
     }
@@ -207,4 +207,37 @@ enumerable switch
         IEnumerable<T> second, Func<T, TKey> keySelector,
         IEqualityComparer<TKey>? comparer = null) =>
         first.IntersectBy(second.Select(keySelector), keySelector, comparer);
+
+
+    /// <summary>
+    /// Return empty if collection is null
+    /// </summary>
+    /// <param name="enumerable"></param>
+    /// <returns></returns>
+    public static IEnumerable<T> EmptyIfNull<T>(this IEnumerable<T>? enumerable) =>
+        enumerable ?? Enumerable.Empty<T>();
+
+    /// <summary>
+    /// Return empty if array is null
+    /// </summary>
+    /// <param name="array"></param>
+    /// <returns></returns>
+    public static T[] EmptyIfNull<T>(this T[]? array) =>
+        array ?? Array.Empty<T>();
+
+    /// <summary>
+    /// Return empty if array is null
+    /// </summary>
+    /// <param name="array"></param>
+    /// <returns></returns>
+    public static IReadOnlyCollection<T> EmptyIfNull<T>(this IReadOnlyCollection<T>? array) =>
+        array ?? Array.Empty<T>();
+
+    /// <summary>
+    /// Return empty if array is null
+    /// </summary>
+    /// <param name="array"></param>
+    /// <returns></returns>
+    public static IReadOnlyList<T> EmptyIfNull<T>(this IReadOnlyList<T>? array) =>
+        array ?? Array.Empty<T>();
 }

tests/CSharpPlus.Tests/EnumerablePlus/LinqEnumerablePlusTests.cs

@@ -1,5 +1,6 @@
 // ReSharper disable PossibleMultipleEnumeration
 
+using System.Collections.ObjectModel;
 using FsCheck;
 
 namespace CSharpPlus.Tests.EnumerablePlus;
@@ -228,4 +229,20 @@ public void ShouldIntersectBySelector()
             both1, both2,
         });
     }
+
+    [Test]
+    public void ShouldBeEmptyIfNull() =>
+        (null as IEnumerable<int>).EmptyIfNull().Should().BeEmpty();
+
+    [Test]
+    public void ShouldBeEmptyArrayIfNull() =>
+        (null as int[]).EmptyIfNull().Should().BeEmpty();
+
+    [Test]
+    public void ShouldBeEmptyCollectionIfNull() =>
+        (null as ReadOnlyCollection<int>).EmptyIfNull().Should().BeEmpty();
+
+    [Test]
+    public void ShouldBeEmptyListIfNull() =>
+        (null as IReadOnlyList<int>).EmptyIfNull().Should().BeEmpty();
 }