Akka.Streams.Tests.IO.FileSinkSpec.SynchronousFileSink_should_by_default_write_into_existing_file C# (CSharp) Метод

        public void SynchronousFileSink_should_by_default_write_into_existing_file()
        {
            this.AssertAllStagesStopped(() =>
            {
                TargetFile(f =>
                {
                    Func<IEnumerable<string>, Task<IOResult>> write = lines => Source.From(lines)
                        .Select(ByteString.FromString)
                        .RunWith(FileIO.ToFile(f), _materializer);

                    var completion1 = write(_testLines);
                    completion1.Wait(TimeSpan.FromSeconds(3)).Should().BeTrue();

                    var lastWrite = new string[100];
                    for (var i = 0; i < 100; i++)
                        lastWrite[i] = "x";

                    var completion2 = write(lastWrite);
                    completion2.Wait(TimeSpan.FromSeconds(3)).Should().BeTrue();
                    var result = completion2.Result;

                    var lastWriteString = new string(lastWrite.SelectMany(x => x).ToArray());
                    result.Count.Should().Be(lastWriteString.Length);
                    var testLinesString = new string(_testLines.SelectMany(x => x).ToArray());
                    CheckFileContent(f, lastWriteString + testLinesString.Substring(100));
                });
            }, _materializer);
        }