Change TarReader constructor exception if unreadable stream. Close te…

…st gap.

src/libraries/System.Formats.Tar/src/System/Formats/Tar/TarReader.cs

@@ -28,14 +28,15 @@ public sealed class TarReader : IDisposable, IAsyncDisposable
         /// </summary>
         /// <param name="archiveStream">The stream to read from.</param>
         /// <param name="leaveOpen"><see langword="false"/> to dispose the <paramref name="archiveStream"/> when this instance is disposed; <see langword="true"/> to leave the stream open.</param>
-        /// <exception cref="IOException"><paramref name="archiveStream"/> is unreadable.</exception>
+        /// <exception cref="ArgumentException"><paramref name="archiveStream"/> is unreadable.</exception>
+        /// <exception cref="ArgumentNullException"><paramref name="archiveStream"/> is <see langword="null"/>.</exception>
         public TarReader(Stream archiveStream, bool leaveOpen = false)
         {
             ArgumentNullException.ThrowIfNull(archiveStream);
 
             if (!archiveStream.CanRead)
             {
-                throw new IOException(SR.IO_NotSupported_UnreadableStream);
+                throw new ArgumentException(SR.IO_NotSupported_UnreadableStream, nameof(archiveStream));
             }
 
             _archiveStream = archiveStream;

src/libraries/System.Formats.Tar/tests/System.Formats.Tar.Tests.csproj

@@ -40,6 +40,7 @@
     <Compile Include="TarReader\TarReader.TarEntry.ExtractToFile.Tests.cs" />
     <Compile Include="TarReader\TarReader.File.Tests.cs" />
     <Compile Include="TarReader\TarReader.GetNextEntry.Tests.cs" />
+    <Compile Include="TarReader\TarReader.Tests.cs" />
     <Compile Include="TarTestsBase.cs" />
     <Compile Include="TarTestsBase.Gnu.cs" />
     <Compile Include="TarTestsBase.Pax.cs" />

src/libraries/System.Formats.Tar/tests/TarReader/TarReader.Tests.cs

@@ -0,0 +1,99 @@
+using System.Xml.Linq;
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.Generic;
+using System.IO;
+using Xunit;
+using System.Linq;
+
+namespace System.Formats.Tar.Tests
+{
+    public class TarReader_Tests : TarTestsBase
+    {
+        [Fact]
+        public void TarReader_NullArchiveStream() => Assert.Throws<ArgumentNullException>(() => new TarReader(archiveStream: null));
+
+        [Fact]
+        public void TarReader_UnreadableStream()
+        {
+            using MemoryStream ms = new MemoryStream();
+            using WrappedStream ws = new WrappedStream(ms, canRead: false, canWrite: true, canSeek: true);
+            Assert.Throws<ArgumentException>(() => new TarReader(ws));
+        }
+
+        [Fact]
+        public void TarReader_LeaveOpen_False()
+        {
+            using MemoryStream ms = GetTarMemoryStream(CompressionMethod.Uncompressed, TestTarFormat.pax, "many_small_files");
+            List<Stream> dataStreams = new List<Stream>();
+            using (TarReader reader = new TarReader(ms, leaveOpen: false))
+            {
+                TarEntry entry;
+                while ((entry = reader.GetNextEntry()) != null)
+                {
+                    if (entry.DataStream != null)
+                    {
+                        dataStreams.Add(entry.DataStream);
+                    }
+                }
+            }
+
+            Assert.True(dataStreams.Any());
+            foreach (Stream ds in dataStreams)
+            {
+                Assert.Throws<ObjectDisposedException>(() => ds.ReadByte());
+            }
+        }
+
+        [Fact]
+        public void TarReader_LeaveOpen_True()
+        {
+            using MemoryStream ms = GetTarMemoryStream(CompressionMethod.Uncompressed, TestTarFormat.pax, "many_small_files");
+            List<Stream> dataStreams = new List<Stream>();
+            using (TarReader reader = new TarReader(ms, leaveOpen: true))
+            {
+                TarEntry entry;
+                while ((entry = reader.GetNextEntry()) != null)
+                {
+                    if (entry.DataStream != null)
+                    {
+                        dataStreams.Add(entry.DataStream);
+                    }
+                }
+            }
+
+            Assert.True(dataStreams.Any());
+            foreach (Stream ds in dataStreams)
+            {
+                ds.ReadByte(); // Should not throw
+                ds.Dispose();
+            }
+        }
+
+        [Fact]
+        public void TarReader_LeaveOpen_False_CopiedDataNotDisposed()
+        {
+            using MemoryStream ms = GetTarMemoryStream(CompressionMethod.Uncompressed, TestTarFormat.pax, "many_small_files");
+            List<Stream> dataStreams = new List<Stream>();
+            using (TarReader reader = new TarReader(ms, leaveOpen: false))
+            {
+                TarEntry entry;
+                while ((entry = reader.GetNextEntry(copyData: true)) != null)
+                {
+                    if (entry.DataStream != null)
+                    {
+                        dataStreams.Add(entry.DataStream);
+                    }
+                }
+            }
+
+            Assert.True(dataStreams.Any());
+            foreach (Stream ds in dataStreams)
+            {
+                ds.ReadByte(); // Should not throw, copied streams, user should dispose
+                ds.Dispose();
+            }
+        }
+    }
+}