From 31cff16ecebca43c55c8b22c172aa1e16c992fba Mon Sep 17 00:00:00 2001
From: MrSmoke <709976+MrSmoke@users.noreply.github.com>
Date: Wed, 11 Mar 2026 18:40:50 +1100
Subject: [PATCH 1/2] Add AsReadOnlyCollection

---
 .../src/Extensions/EnumerableExtensions.cs    | 64 +++++++++++++------
 .../Extensions/EnumerableExtensionTests.cs    | 31 ++++++++-
 2 files changed, 72 insertions(+), 23 deletions(-)

diff --git a/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs b/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
index 80aa7f9..2cc766e 100644
--- a/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
+++ b/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
@@ -15,7 +15,7 @@ public static partial class EnumerableExtensions
     /// <param name="source"></param>
     /// <param name="value">The first element if found</param>
     /// <typeparam name="T"></typeparam>
-    /// <returns>True if element contains an item, otherwise false</returns>
+    /// <returns>True if <paramref name="source"/> contains an item, otherwise false</returns>
     /// <exception cref="ArgumentNullException"></exception>
     public static bool TryGetFirstValue<T>(this IEnumerable<T> source, [MaybeNullWhen(false)] out T value)
     {
@@ -59,44 +59,67 @@ public static bool TryGetFirstValue<T>(this IEnumerable<T> source, [MaybeNullWhe
     /// <summary>
     /// Casts a sequence to an <see cref="ICollection{T}"/>, otherwise enumerates the sequence.
     /// </summary>
-    /// <param name="enumerable"></param>
+    /// <param name="source"></param>
     /// <typeparam name="T"></typeparam>
     /// <returns></returns>
-    public static ICollection<T> AsCollection<T>(this IEnumerable<T> enumerable)
+    public static ICollection<T> AsCollection<T>(this IEnumerable<T> source)
     {
-        if (enumerable is ICollection<T> collection)
+        if (source is null)
+            throw new ArgumentNullException(nameof(source));
+
+        if (source is ICollection<T> collection)
             return collection;
 
-        return enumerable.ToList();
+        return source.ToList();
     }
 
     /// <summary>
     /// Casts a sequence to a <see cref="IReadOnlyList{T}"/>, otherwise enumerates the sequence.
     /// </summary>
-    /// <param name="enumerable"></param>
+    /// <param name="source"></param>
     /// <typeparam name="T"></typeparam>
     /// <returns></returns>
-    public static IReadOnlyList<T> AsReadOnlyList<T>(this IEnumerable<T> enumerable)
+    public static IReadOnlyList<T> AsReadOnlyList<T>(this IEnumerable<T> source)
     {
-        if (enumerable is IReadOnlyList<T> collection)
+        if (source is null)
+            throw new ArgumentNullException(nameof(source));
+
+        if (source is IReadOnlyList<T> collection)
             return collection;
 
-        return new ReadOnlyCollection<T>(enumerable.ToList());
+        return new ReadOnlyCollection<T>(source.ToList());
+    }
+
+    /// <summary>
+    /// Casts a sequence to a <see cref="IReadOnlyCollection{T}" />, otherwise enumerates the sequence.
+    /// </summary>
+    /// <param name="source"></param>
+    /// <typeparam name="T"></typeparam>
+    /// <returns></returns>
+    public static IReadOnlyCollection<T> AsReadOnlyCollection<T>(this IEnumerable<T> source)
+    {
+        if (source is null)
+            throw new ArgumentNullException(nameof(source));
+
+        if (source is IReadOnlyCollection<T> collection)
+            return collection;
+
+        return new ReadOnlyCollection<T>(source.ToList());
     }
 
     /// <summary>
     /// Enumerates a sequence and returns only non null values
     /// </summary>
-    /// <param name="enumerable"></param>
+    /// <param name="source"></param>
     /// <typeparam name="T"></typeparam>
     /// <returns></returns>
     /// <exception cref="ArgumentNullException"></exception>
-    public static IEnumerable<T> WhereNotNull<T>(this IEnumerable<T?> enumerable) where T : class
+    public static IEnumerable<T> WhereNotNull<T>(this IEnumerable<T?> source)
     {
-        if (enumerable is null)
-            throw new ArgumentNullException(nameof(enumerable));
+        if (source is null)
+            throw new ArgumentNullException(nameof(source));
 
-        foreach (var t in enumerable)
+        foreach (var t in source)
         {
             if (t is not null)
                 yield return t;
@@ -106,27 +129,26 @@ public static IEnumerable<T> WhereNotNull<T>(this IEnumerable<T?> enumerable) wh
     /// <summary>
     /// Enumerates a sequence and returns only non null values
     /// </summary>
-    /// <param name="enumerable"></param>
+    /// <param name="source"></param>
     /// <param name="selector"></param>
     /// <typeparam name="T"></typeparam>
     /// <typeparam name="TResult"></typeparam>
     /// <returns></returns>
     /// <exception cref="ArgumentNullException"></exception>
     public static IEnumerable<TResult> WhereNotNull<T, TResult>(
-        this IEnumerable<T> enumerable,
+        this IEnumerable<T> source,
         Func<T, TResult?> selector)
-        where TResult : class
     {
-        if (enumerable is null)
-            throw new ArgumentNullException(nameof(enumerable));
+        if (source is null)
+            throw new ArgumentNullException(nameof(source));
 
         if (selector is null)
             throw new ArgumentNullException(nameof(selector));
 
-        foreach (var t in enumerable.Select(selector))
+        foreach (var t in source.Select(selector))
         {
             if (t is not null)
                 yield return t;
         }
     }
-}
\ No newline at end of file
+}
diff --git a/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs b/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
index fdabecb..87af208 100644
--- a/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
+++ b/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
@@ -18,7 +18,7 @@ public void TryGetFirstValue_Array()
     public void TryGetFirstValue_Enumerable()
     {
         // Where() to force an Enumerable
-        IEnumerable<int> list = Enumerable.Range(1, 100).Where(x => true);
+        var list = Enumerable.Range(1, 100).Where(x => true);
 
         Assert.True(list.TryGetFirstValue(out var value));
         Assert.Equal(1, value);
@@ -36,8 +36,35 @@ public void TryGetFirstValue_Empty()
     public void TryGetFirstValue_EmptyEnumerable()
     {
         // Where() to force an Enumerable
-        IEnumerable<int> list = Enumerable.Range(1, 100).Where(x => false);
+        var list = Enumerable.Range(1, 100).Where(x => false);
 
         Assert.False(list.TryGetFirstValue(out _));
     }
+
+    [Fact]
+    public void WhereNotNull_ValueTypeListContainsNull_ReturnsNoNullValues()
+    {
+        int?[] list = [1, null, 2, null, 3];
+
+        var result = list.WhereNotNull().ToList();
+
+        Assert.All(result, i => Assert.NotNull(i));
+        Assert.NotEqual(list.Length, result.Count);
+    }
+
+    [Fact]
+    public void WhereNotNull_SelectorClassTypeListContainsNull_ReturnsNoNullValues()
+    {
+        Test[] list = [new("1"), new(null)];
+
+        var result = list.WhereNotNull(x => x.Value).ToList();
+
+        Assert.All(result, Assert.NotNull);
+        Assert.NotEqual(list.Length, result.Count);
+    }
+
+    private class Test(string? value)
+    {
+        public string? Value { get; } = value;
+    }
 }

From 36600cb6b0ff9a566e21b03b40d2ed72d6b80042 Mon Sep 17 00:00:00 2001
From: MrSmoke <709976+MrSmoke@users.noreply.github.com>
Date: Wed, 11 Mar 2026 19:01:47 +1100
Subject: [PATCH 2/2] Use ToArray over ToList when enumerating

---
 .../src/Extensions/EnumerableExtensions.cs      | 17 ++++++++---------
 .../test/Extensions/EnumerableExtensionTests.cs | 12 +++++-------
 2 files changed, 13 insertions(+), 16 deletions(-)

diff --git a/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs b/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
index 2cc766e..fed404b 100644
--- a/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
+++ b/src/Primitives/Primitives/src/Extensions/EnumerableExtensions.cs
@@ -3,7 +3,6 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Collections.ObjectModel;
 using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 
@@ -30,11 +29,11 @@ public static bool TryGetFirstValue<T>(this IEnumerable<T> source, [MaybeNullWhe
             return false;
         }
 #else
-            if (source is ICollection<T> {Count: 0} or ICollection {Count: 0})
-            {
-                value = default;
-                return false;
-            }
+        if (source is ICollection<T> {Count: 0} or ICollection {Count: 0})
+        {
+            value = default;
+            return false;
+        }
 #endif
 
         if (source is IList<T> list)
@@ -70,7 +69,7 @@ public static ICollection<T> AsCollection<T>(this IEnumerable<T> source)
         if (source is ICollection<T> collection)
             return collection;
 
-        return source.ToList();
+        return source.ToArray();
     }
 
     /// <summary>
@@ -87,7 +86,7 @@ public static IReadOnlyList<T> AsReadOnlyList<T>(this IEnumerable<T> source)
         if (source is IReadOnlyList<T> collection)
             return collection;
 
-        return new ReadOnlyCollection<T>(source.ToList());
+        return source.ToArray();
     }
 
     /// <summary>
@@ -104,7 +103,7 @@ public static IReadOnlyCollection<T> AsReadOnlyCollection<T>(this IEnumerable<T>
         if (source is IReadOnlyCollection<T> collection)
             return collection;
 
-        return new ReadOnlyCollection<T>(source.ToList());
+        return source.ToArray();
     }
 
     /// <summary>
diff --git a/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs b/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
index 87af208..f297276 100644
--- a/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
+++ b/src/Primitives/Primitives/test/Extensions/EnumerableExtensionTests.cs
@@ -46,21 +46,19 @@ public void WhereNotNull_ValueTypeListContainsNull_ReturnsNoNullValues()
     {
         int?[] list = [1, null, 2, null, 3];
 
-        var result = list.WhereNotNull().ToList();
+        var result = list.WhereNotNull();
 
-        Assert.All(result, i => Assert.NotNull(i));
-        Assert.NotEqual(list.Length, result.Count);
+        Assert.Equal(result, [1, 2, 3]);
     }
 
     [Fact]
     public void WhereNotNull_SelectorClassTypeListContainsNull_ReturnsNoNullValues()
     {
-        Test[] list = [new("1"), new(null)];
+        Test[] list = [new("1"), new(null), new("2"), new(null)];
 
-        var result = list.WhereNotNull(x => x.Value).ToList();
+        var result = list.WhereNotNull(x => x.Value);
 
-        Assert.All(result, Assert.NotNull);
-        Assert.NotEqual(list.Length, result.Count);
+        Assert.Equal(result, ["1", "2"]);
     }
 
     private class Test(string? value)