public async Task CreateOrAppendTextWorksWithExistingFile() { // --- Arrange const string BODY = "FirstSecond"; var wfs = new WindowsFileStorage(ROOT); var file = new AbstractFileDescriptor("Container", null, "TestFile.txt"); var fileName = WindowsFileStorage.FilePathFromAbstractFile(file); if (File.Exists(fileName)) { File.Delete(fileName); } using (var textFile = await wfs.CreateTextAsync(file)) { textFile.Writer.Write("First"); } // --- Act using (var textFile = await wfs.CreateOrAppendTextAsync(file)) { textFile.Writer.Write("Second"); } // --- Assert using (var savedFile = await wfs.OpenTextAsync(file)) { var text = savedFile.Reader.ReadToEnd(); text.ShouldBe(BODY); } }