System.IO.Compression.DeflateStream.WriteAsync C# (CSharp) Method

        public override Task WriteAsync(byte[] array, int offset, int count, CancellationToken cancellationToken)
        {
            // We use this checking order for compat to earlier versions:
            EnsureCompressionMode();
            EnsureNoActiveAsyncOperation();
            ValidateParameters(array, offset, count);
            EnsureNotDisposed();

            if (cancellationToken.IsCancellationRequested)
                return Task.FromCanceled<int>(cancellationToken);

            return WriteAsyncCore(array, offset, count, cancellationToken);
        }

        public void Precancellation()
        {
            var ms = new MemoryStream();

            using (Stream compressor = new DeflateStream(ms, CompressionMode.Compress, leaveOpen: true))
            {
                Assert.True(compressor.WriteAsync(new byte[1], 0, 1, new CancellationToken(true)).IsCanceled);
                Assert.True(compressor.FlushAsync(new CancellationToken(true)).IsCanceled);
            }
            using (Stream decompressor = CreateStream(ms, CompressionMode.Decompress, leaveOpen: true))
            {
                Assert.True(decompressor.ReadAsync(new byte[1], 0, 1, new CancellationToken(true)).IsCanceled);
            }
        }