public void AddFilter()
{
var qsb = new QueryStringBuilder();
var key = Guid.NewGuid();
Expression <Func <Person, bool> > exp1 = x => x.Key == key;
qsb.AddFilter(exp1);
var pattern = $"?$filter=Ref_Key eq guid'{key}'&$format=json";
var result = qsb.Build();
Assert.AreEqual(pattern, result);
}
