Reduce code in GroupBy.

Ix.NET/Source/System.Linq.Async/System/Linq/Operators/GroupBy.cs

@@ -11,220 +11,70 @@ namespace System.Linq
 {
     public static partial class AsyncEnumerable
     {
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-
-            return new GroupedAsyncEnumerable<TSource, TKey>(source, keySelector, comparer: null);
-        }
-
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-
-            return new GroupedAsyncEnumerable<TSource, TKey>(source, keySelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector) =>
+            GroupedAsyncEnumerable<TSource, TKey>(source, keySelector, comparer: null);
 
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerable<TSource, TKey>(source, keySelector, comparer);
 
-            return new GroupedAsyncEnumerableWithTask<TSource, TKey>(source, keySelector, comparer: null);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector) =>
+            new GroupedAsyncEnumerableWithTask<TSource, TKey>(source, keySelector, comparer: null);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-
-            return new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey>(source, keySelector, comparer: null);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector) =>
+            new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey>(source, keySelector, comparer: null);
 #endif
 
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-
-            return new GroupedAsyncEnumerableWithTask<TSource, TKey>(source, keySelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerableWithTask<TSource, TKey>(source, keySelector, comparer);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-
-            return new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey>(source, keySelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TSource>> GroupBy<TSource, TKey>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey>(source, keySelector, comparer);
 #endif
 
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
-
-            return new GroupedAsyncEnumerable<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
-        }
-
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
-
-            return new GroupedAsyncEnumerable<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector) =>
+            new GroupedAsyncEnumerable<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
 
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TSource, ValueTask<TElement>> elementSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerable<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
 
-            return new GroupedAsyncEnumerableWithTask<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TSource, ValueTask<TElement>> elementSelector) =>
+            new GroupedAsyncEnumerableWithTask<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TSource, CancellationToken, ValueTask<TElement>> elementSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
-
-            return new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TSource, CancellationToken, ValueTask<TElement>> elementSelector) =>
+            new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer: null);
 #endif
 
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TSource, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
-
-            return new GroupedAsyncEnumerableWithTask<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TSource, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerableWithTask<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TSource, CancellationToken, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (elementSelector == null)
-                throw Error.ArgumentNull(nameof(elementSelector));
-
-            return new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
-        }
+        public static IAsyncEnumerable<IAsyncGrouping<TKey, TElement>> GroupBy<TSource, TKey, TElement>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TSource, CancellationToken, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TElement>(source, keySelector, elementSelector, comparer);
 #endif
 
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
-
-            return new GroupedResultAsyncEnumerable<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
-        }
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector) =>
+            new GroupedResultAsyncEnumerable<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
 
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedResultAsyncEnumerable<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
 
-            return new GroupedResultAsyncEnumerable<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
-        }
-
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, ValueTask<TResult>> resultSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
-
-            return new GroupedResultAsyncEnumerableWithTask<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
-        }
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, ValueTask<TResult>> resultSelector) =>
+            new GroupedResultAsyncEnumerableWithTask<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, CancellationToken, ValueTask<TResult>> resultSelector)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
-
-            return new GroupedResultAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
-        }
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, CancellationToken, ValueTask<TResult>> resultSelector) =>
+            new GroupedResultAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer: null);
 #endif
 
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
-
-            return new GroupedResultAsyncEnumerableWithTask<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
-        }
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedResultAsyncEnumerableWithTask<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
 
 #if !NO_DEEP_CANCELLATION
-        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer)
-        {
-            if (source == null)
-                throw Error.ArgumentNull(nameof(source));
-            if (keySelector == null)
-                throw Error.ArgumentNull(nameof(keySelector));
-            if (resultSelector == null)
-                throw Error.ArgumentNull(nameof(resultSelector));
-
-            return new GroupedResultAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
-        }
+        public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer) =>
+            new GroupedResultAsyncEnumerableWithTaskAndCancellation<TSource, TKey, TResult>(source, keySelector, resultSelector, comparer);
 #endif
 
         public static IAsyncEnumerable<TResult> GroupBy<TSource, TKey, TElement, TResult>(this IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, Func<TKey, IAsyncEnumerable<TElement>, TResult> resultSelector)
@@ -327,13 +177,9 @@ namespace System.Linq
 
             public GroupedResultAsyncEnumerable(IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TKey, IAsyncEnumerable<TSource>, TResult> resultSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(resultSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _resultSelector = resultSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _resultSelector = resultSelector ?? throw Error.ArgumentNull(nameof(resultSelector));
                 _comparer = comparer;
             }
 
@@ -420,13 +266,9 @@ namespace System.Linq
 
             public GroupedResultAsyncEnumerableWithTask(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(resultSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _resultSelector = resultSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _resultSelector = resultSelector ?? throw Error.ArgumentNull(nameof(resultSelector));
                 _comparer = comparer;
             }
 
@@ -514,13 +356,9 @@ namespace System.Linq
 
             public GroupedResultAsyncEnumerableWithTaskAndCancellation(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TKey, IAsyncEnumerable<TSource>, CancellationToken, ValueTask<TResult>> resultSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(resultSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _resultSelector = resultSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _resultSelector = resultSelector ?? throw Error.ArgumentNull(nameof(resultSelector));
                 _comparer = comparer;
             }
 
@@ -608,13 +446,9 @@ namespace System.Linq
 
             public GroupedAsyncEnumerable(IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(elementSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _elementSelector = elementSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _elementSelector = elementSelector ?? throw Error.ArgumentNull(nameof(elementSelector));
                 _comparer = comparer;
             }
 
@@ -701,13 +535,9 @@ namespace System.Linq
 
             public GroupedAsyncEnumerableWithTask(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, Func<TSource, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(elementSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _elementSelector = elementSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _elementSelector = elementSelector ?? throw Error.ArgumentNull(nameof(elementSelector));
                 _comparer = comparer;
             }
 
@@ -795,13 +625,9 @@ namespace System.Linq
 
             public GroupedAsyncEnumerableWithTaskAndCancellation(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, Func<TSource, CancellationToken, ValueTask<TElement>> elementSelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-                Debug.Assert(elementSelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
-                _elementSelector = elementSelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
+                _elementSelector = elementSelector ?? throw Error.ArgumentNull(nameof(elementSelector));
                 _comparer = comparer;
             }
 
@@ -888,11 +714,8 @@ namespace System.Linq
 
             public GroupedAsyncEnumerable(IAsyncEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
                 _comparer = comparer;
             }
 
@@ -978,11 +801,8 @@ namespace System.Linq
 
             public GroupedAsyncEnumerableWithTask(IAsyncEnumerable<TSource> source, Func<TSource, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
                 _comparer = comparer;
             }
 
@@ -1069,11 +889,8 @@ namespace System.Linq
 
             public GroupedAsyncEnumerableWithTaskAndCancellation(IAsyncEnumerable<TSource> source, Func<TSource, CancellationToken, ValueTask<TKey>> keySelector, IEqualityComparer<TKey> comparer)
             {
-                Debug.Assert(source != null);
-                Debug.Assert(keySelector != null);
-
-                _source = source;
-                _keySelector = keySelector;
+                _source = source ?? throw Error.ArgumentNull(nameof(source));
+                _keySelector = keySelector ?? throw Error.ArgumentNull(nameof(keySelector));
                 _comparer = comparer;
             }