How to create Test data for NUNIT testing

These are WCF services with basichttp binding

Following is the follow
NUNIT test case -> WCF client(classlib) -> WCF service

[Test]
public void TestAddBO()
{
BOclass obj = new BOclass();
...
...
var result = _serviceclient.AddBO(obj);
 Assert.IsTrue(result.Success);
}

We wanna create test data for above method and similarly for GetList of BO objects as well