public async Task ShouldWrite()
{
using (var stream = fileStreamFactory.CreateOutputStream("output.properties", OutputType.yaml))
{
stream.ShouldBeOfType <FileStream>();
using (var writer = new StreamWriter(stream))
await writer.WriteAsync("asdfgh");
}
var text = await File.ReadAllTextAsync(Path.Combine(tempDirectoryName, "output.properties"));
text.ShouldBe("asdfgh");
}