public void Should_not_be_able_to_add_Policy_with_duplicate_key_using_Add()
{
Policy policy = Policy.NoOp();
string key = Guid.NewGuid().ToString();
_registry.Invoking(r => r.Add(key, policy))
.Should().NotThrow();
_registry.Invoking(r => r.Add(key, policy))
.Should().Throw <ArgumentException>();
_registry.Count.Should().Be(1);
}