private static HttpClient CreateHttpClient(Func<RequestContext, int> getMaxContentLength) { var app = new AppBuilder(); app.MaxRequestContentLength(getMaxContentLength) .Use(async (context, _) => { await new StreamReader(context.Request.Body).ReadToEndAsync(); await new StreamWriter(context.Response.Body).WriteAsync("Lorem ipsum"); context.Response.StatusCode = 200; context.Response.ReasonPhrase = "OK"; }); return new HttpClient(new OwinHttpMessageHandler(app.Build())) { BaseAddress = new Uri("http://example.com") }; }