Imported Upstream version 4.8.0.425

Former-commit-id: 56934f10a9ad11e3eb75c21da859e02f54766140

mcs/class/System.IO.Compression/Test/System.IO.Compression/ZipTest.cs

@@ -507,6 +507,11 @@ namespace MonoTests.System.IO.Compression
 			/// Simulate "CanSeek" is false, which is the case when you are retreiving data from web.
 			/// </summary>
 			public override bool CanSeek => false;
+
+			public override long Position {
+				get {throw new NotSupportedException();}
+				set {throw new NotSupportedException();}
+			}
 		}
 
 		[Test]
@@ -517,5 +522,16 @@ namespace MonoTests.System.IO.Compression
 			{
 			}
 		}
+
+		[Test]
+		public void ZipWriteNonSeekableStream() {
+			var stream = new MyFakeStream( "test.nupkg", FileMode.Open );
+			using ( var archive = new ZipArchive( stream, ZipArchiveMode.Create ) ) {
+				var entry = archive.CreateEntry( "foo" );
+				using ( var es = entry.Open() ) {
+					es.Write( new byte[] { 4, 2 }, 0, 2 );
+				}
+			}
+		}
 	}
 }