Fix GZip write async

src/SharpCompress/Archives/GZip/GZipArchiveEntry.cs

@@ -24,7 +24,7 @@ public virtual Stream OpenEntryStream()
         return Parts.Single().GetCompressedStream().NotNull();
     }
 
-    public async ValueTask<Stream> OpenEntryStreamAsync(
+    public virtual async ValueTask<Stream> OpenEntryStreamAsync(
         CancellationToken cancellationToken = default
     )
     {

src/SharpCompress/Archives/GZip/GZipWritableArchiveEntry.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Collections.Generic;
 using System.IO;
+using System.Threading;
+using System.Threading.Tasks;
 using SharpCompress.Common;
 using SharpCompress.IO;
 
@@ -61,6 +63,14 @@ public override Stream OpenEntryStream()
         return SharpCompressStream.CreateNonDisposing(stream);
     }
 
+    public override ValueTask<Stream> OpenEntryStreamAsync(
+        CancellationToken cancellationToken = default
+    )
+    {
+        cancellationToken.ThrowIfCancellationRequested();
+        return new(OpenEntryStream());
+    }
+
     internal override void Close()
     {
         if (closeStream)

tests/SharpCompress.Test/GZip/GZipArchiveAsyncTests.cs

@@ -6,6 +6,8 @@
 using SharpCompress.Archives.GZip;
 using SharpCompress.Archives.Tar;
 using SharpCompress.Common;
+using SharpCompress.Compressors.Deflate;
+using SharpCompress.Readers;
 using SharpCompress.Test.Mocks;
 using SharpCompress.Writers.GZip;
 using Xunit;
@@ -181,4 +183,37 @@ public async Task TestGzArchiveTypeGzip_Async()
         await using var archive = await GZipArchive.OpenAsyncArchive(new AsyncOnlyStream(stream));
         Assert.Equal(archive.Type, ArchiveType.GZip);
     }
+
+    [Fact]
+    public async ValueTask GZip_Create_New_Async()
+    {
+        var scratchPath = Path.Combine(SCRATCH_FILES_PATH, Guid.NewGuid().ToString());
+        var filePath = Path.Combine(scratchPath, "test.gz");
+        if (!Directory.Exists(scratchPath))
+        {
+            Directory.CreateDirectory(scratchPath);
+        }
+        await using (var archive = (GZipArchive)await GZipArchive.CreateAsyncArchive())
+        {
+            await archive.AddEntryAsync("Tar.tar", Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar"));
+            await archive.SaveToAsync(filePath, new GZipWriterOptions(CompressionLevel.BestSpeed));
+        }
+        var scratchPath2 = Path.Combine(SCRATCH_FILES_PATH, Guid.NewGuid().ToString());
+        if (!Directory.Exists(scratchPath2))
+        {
+            Directory.CreateDirectory(scratchPath2);
+        }
+
+        await using var archive2 = await GZipArchive.OpenAsyncArchive(
+            new AsyncOnlyStream(File.OpenRead(filePath))
+        );
+        await foreach (var entry in archive2.EntriesAsync)
+        {
+            await entry.WriteToDirectoryAsync(scratchPath2);
+        }
+        CompareFilesByPath(
+            Path.Combine(TEST_ARCHIVES_PATH, "Tar.tar"),
+            Path.Combine(scratchPath2, "Tar.tar")
+        );
+    }
 }