Merge pull request #735 from Erior/feature/Expand-Delta-distance-tests

Remove check for minimal distance and add test case generated by 7z as compatibility check

src/SharpCompress/Compressors/Filters/DeltaFilter.cs

@@ -19,11 +19,6 @@ public DeltaFilter(bool isEncoder, Stream baseStream, byte[] info)
             _distance = info[0];
             _history = new byte[DISTANCE_MAX];
             _position = 0;
-
-            if (_distance < DISTANCE_MIN)
-            {
-                throw new NotSupportedException();
-            }
         }
 
         protected override int Transform(byte[] buffer, int offset, int count)

tests/SharpCompress.Test/ArchiveTests.cs

@@ -282,4 +282,29 @@ protected void ArchiveFileReadEx(string testArchive)
         }
         VerifyFilesEx();
     }
+
+    protected void ArchiveDeltaDistanceRead(string testArchive)
+    {
+        testArchive = Path.Combine(TEST_ARCHIVES_PATH, testArchive);
+        using (var archive = Archives.ArchiveFactory.Open(testArchive, null))
+        using (var reader = archive.ExtractAllEntries())
+            while (reader.MoveToNextEntry())
+            {
+                if (!reader.Entry.IsDirectory)
+                {
+                    var memory = new MemoryStream();
+                    reader.WriteEntryTo(memory);
+
+                    memory.Position = 0;
+
+                    for (int y = 0; y < 9; y++)
+                        for (int x = 0; x < 256; x++)
+                        {
+                            Assert.Equal(x, memory.ReadByte());
+                        }
+
+                    Assert.Equal((int)-1, memory.ReadByte());
+                }
+            }
+    }
 }

tests/SharpCompress.Test/SevenZip/SevenZipArchiveTests.cs

@@ -1,4 +1,5 @@
 using System;
+using System.IO;
 using SharpCompress.Common;
 using SharpCompress.Readers;
 using Xunit;
@@ -111,6 +112,9 @@ public class SevenZipArchiveTests : ArchiveTests
     //"7Zip.BZip2.split.007"
 
     [Fact]
-    public void SevenZipArchive_delta_FileRead() =>
+    public void SevenZipArchive_Delta_FileRead() =>
         ArchiveFileRead("7Zip.delta.7z");
+
+    [Fact]
+    public void SevenZipArchive_Delta_Distance() => ArchiveDeltaDistanceRead("7Zip.delta.distance.7z");
 }