public async Task ThrowsWhenStatusCodeIsSetAfterResponseStarted()
{
// Act
await _http1Connection.WriteAsync(new ArraySegment <byte>(new byte[1]));
// Assert
Assert.True(_http1Connection.HasResponseStarted);
Assert.Throws <InvalidOperationException>(() => ((IHttpResponseFeature)_http1Connection).StatusCode = StatusCodes.Status404NotFound);
}