UseFakeMiddleware and UseCountingMiddleware extensions

AppBuilderExtensions.cs

namespace Tests 
{
    using AppFunc = Func<IDictionary<string, object>, Task>;

    public static class AppBuilderExtensions
    {
        /// <summary>
        /// Responds with the given status code (<paramref name="statusCode" />) and given response body (<paramref name="responseBody" />) as text/plain content.
        /// </summary>
        public static IAppBuilder UseFakeMiddleware(this IAppBuilder app, int statusCode, string responseBody)
        {
            return app.Use(new Func<AppFunc, AppFunc>(next => env =>
            {
                var context = new OwinContext(env);
                context.Response.StatusCode = statusCode;
                context.Response.Headers.Add("Content-Type", new [] { "text/plain" });

                return context.Response.WriteAsync(responseBody);
            }));
        }

        /// <summary>
        /// A pass-through middleware to count the hits through <paramref name="increment" />.
        /// </summary>
        public static IAppBuilder UseCountingMiddleware(this IAppBuilder app, Action increment)
        {
            return app.Use(new Func<AppFunc, AppFunc>(next => env =>
            {
                increment();
                return next(env);
            }));
        }
    }
}