public void WhenKeyProviderThenCreatesUntypedWrapper()
{
// arrange
var message = new SomeMessage();
var messageKey = new byte[] { 1, 2 };
var keyProviderMock = new Mock <Func <SomeMessage, string, byte[]> >();
keyProviderMock.Setup(x => x(message, "topic1")).Returns(messageKey);
// act
_pb.KeyProvider(keyProviderMock.Object);
// assert
var keyProvider = _ps.GetKeyProvider();
keyProvider(message, "topic1").Should().BeSameAs(messageKey);
keyProviderMock.Verify(x => x(message, "topic1"), Times.Once);
}