Merge feature/sevenzip-writer-lzma - use CompressionType enum, default LZMA2

src/SharpCompress/Common/CompressionType.cs

@@ -9,6 +9,7 @@ public enum CompressionType
     Deflate,
     Rar,
     LZMA,
+    LZMA2,
     BCJ,
     BCJ2,
     LZip,

src/SharpCompress/Common/SevenZip/SevenZipStreamsCompressor.cs

@@ -29,14 +29,15 @@ internal sealed class SevenZipStreamsCompressor(Stream outputStream)
     /// Returns a PackedStream containing folder metadata, compressed size, and CRCs.
     /// </summary>
     /// <param name="inputStream">Uncompressed data to compress.</param>
-    /// <param name="isLzma2">True for LZMA2, false for LZMA.</param>
+    /// <param name="compressionType">Compression method (LZMA or LZMA2).</param>
     /// <param name="encoderProperties">LZMA encoder properties (null for defaults).</param>
     public PackedStream Compress(
         Stream inputStream,
-        bool isLzma2,
+        CompressionType compressionType,
         LzmaEncoderProperties? encoderProperties = null
     )
     {
+        var isLzma2 = compressionType == CompressionType.LZMA2;
         encoderProperties ??= new LzmaEncoderProperties(eos: !isLzma2);
 
         var outStartOffset = outputStream.Position;

src/SharpCompress/Writers/SevenZip/SevenZipWriter.cs

@@ -77,7 +77,7 @@ public partial class SevenZipWriter : AbstractWriter
         var compressor = new SevenZipStreamsCompressor(OutputStream.NotNull());
         var packed = compressor.Compress(
             progressStream,
-            isLzma2: sevenZipOptions.IsLzma2,
+            sevenZipOptions.CompressionType,
             sevenZipOptions.LzmaProperties
         );
         packedStreams.Add(packed);
@@ -161,7 +161,7 @@ public partial class SevenZipWriter : AbstractWriter
         var headerCompressor = new SevenZipStreamsCompressor(output);
         var headerPacked = headerCompressor.Compress(
             rawHeaderStream,
-            isLzma2: false,
+            CompressionType.LZMA,
             sevenZipOptions.LzmaProperties
         );
 

src/SharpCompress/Writers/SevenZip/SevenZipWriterOptions.cs

@@ -15,12 +15,22 @@ public sealed record SevenZipWriterOptions : IWriterOptions
     private int _compressionLevel;
 
     /// <summary>
-    /// The compression type to use. Supported: LZMA (default), LZMA2 (via CompressionType.LZMA with IsLzma2=true).
+    /// The compression type to use. Supported: LZMA and LZMA2 (default).
     /// </summary>
     public CompressionType CompressionType
     {
         get => _compressionType;
-        init => _compressionType = value;
+        init
+        {
+            if (value != CompressionType.LZMA && value != CompressionType.LZMA2)
+            {
+                throw new ArgumentException(
+                    $"SevenZipWriter only supports CompressionType.LZMA and CompressionType.LZMA2. Got: {value}",
+                    nameof(value)
+                );
+            }
+            _compressionType = value;
+        }
     }
 
     /// <summary>
@@ -54,11 +64,6 @@ public sealed record SevenZipWriterOptions : IWriterOptions
     public CompressionProviderRegistry Providers { get; init; } =
         CompressionProviderRegistry.Default;
 
-    /// <summary>
-    /// Whether to use LZMA2 instead of LZMA. Default is false (LZMA).
-    /// </summary>
-    public bool IsLzma2 { get; init; }
-
     /// <summary>
     /// Whether to compress the archive header itself using LZMA.
     /// Default is true, matching standard 7-Zip behavior.
@@ -71,11 +76,11 @@ public sealed record SevenZipWriterOptions : IWriterOptions
     public LzmaEncoderProperties? LzmaProperties { get; init; }
 
     /// <summary>
-    /// Creates a new SevenZipWriterOptions instance with LZMA compression.
+    /// Creates a new SevenZipWriterOptions instance with LZMA2 compression (default).
     /// </summary>
     public SevenZipWriterOptions()
     {
-        CompressionType = CompressionType.LZMA;
+        CompressionType = CompressionType.LZMA2;
     }
 
     /// <summary>

tests/SharpCompress.Test/SevenZip/SevenZipWriterTests.cs

@@ -168,7 +168,7 @@ public class SevenZipWriterTests : TestBase
 
         using (var writer = new SevenZipWriter(
             archiveStream,
-            new SevenZipWriterOptions { IsLzma2 = true }
+            new SevenZipWriterOptions(CompressionType.LZMA2)
         ))
         {
             using var source = new MemoryStream(content);
@@ -206,7 +206,7 @@ public class SevenZipWriterTests : TestBase
 
         using (var writer = new SevenZipWriter(
             archiveStream,
-            new SevenZipWriterOptions { IsLzma2 = true }
+            new SevenZipWriterOptions(CompressionType.LZMA2)
         ))
         {
             foreach (var (name, text) in files)
@@ -251,7 +251,7 @@ public class SevenZipWriterTests : TestBase
 
         using (var writer = new SevenZipWriter(
             archiveStream,
-            new SevenZipWriterOptions { IsLzma2 = true }
+            new SevenZipWriterOptions(CompressionType.LZMA2)
         ))
         {
             using var source = new MemoryStream(content);
@@ -288,7 +288,7 @@ public class SevenZipWriterTests : TestBase
 
         using (var writer = new SevenZipWriter(
             archiveStream,
-            new SevenZipWriterOptions { IsLzma2 = true }
+            new SevenZipWriterOptions(CompressionType.LZMA2)
         ))
         {
             using var source = new MemoryStream(content);
@@ -311,6 +311,14 @@ public class SevenZipWriterTests : TestBase
         }
     }
 
+    [Fact]
+    public void SevenZipWriter_UnsupportedCompressionType_Throws()
+    {
+        Assert.Throws<ArgumentException>(
+            () => new SevenZipWriterOptions(CompressionType.Deflate)
+        );
+    }
+
     [Fact]
     public void SevenZipWriter_UncompressedHeader_RoundTrip()
     {