System.NotImplementedException :
Portable Bait And Switch is nuget feature, so the package must be installed in all project.

NotImplementedException will indicate that Portable Code from PCL is used and not Platform Specific
implementation. Please check whether platform specific Assembly is properly installed.

Cannot save account in Portable profile - bait-and-switch error.
Please file a bug in https://bugzilla.xamarin.com

AccountStore store;
 store = AccountStore.Create();

using System;
using NUnit.Framework;
using CrowdWisdom;
using CrowdWisdom.Authentication;

namespace CrowdWisdomTest
{
    [TestFixture()]
    public class AuthServiceTest
    {
        [Test()]
        public void SaveRestoreSecret()
        {
            String secret = "ABCD";
            AuthService auth = AuthService.GetInstance();
            auth.putSecret("MySecret", secret);
            Assert.AreEqual(secret, auth.GetSecret("MySecret"));
    }
  }
}