public void ShouldAppendToFile(FileSystem fileSystem, String basePath)
{
var content = Guid.NewGuid().ToString();
var content2 = Guid.NewGuid().ToString();
var path = Path.Combine(basePath, Path.GetRandomFileName());
fileSystem.WriteTextFileAsync(path, content).RunSynchronously();
Assert.AreEqual(content, fileSystem.ReadTextFileAsync(path).RunSynchronously());
fileSystem.AppendTextFileAsync(path, content2).RunSynchronously();
Assert.AreEqual(content + content2, fileSystem.ReadTextFileAsync(path).RunSynchronously());
}