Assert.IsNotAssignableFrom - jnm2/nunit-docs-wiki GitHub Wiki
Assert.IsNotAssignableFrom succeeds if the object provided may not be assigned a value of the expected type.
Assert.IsNotAssignableFrom(Type expected, object actual);
Assert.IsNotAssignableFrom(Type expected, object actual,
string message, params object[] parms);
Assert.IsNotAssignableFrom<T>(object actual);
Assert.IsNotAssignableFrom<T>(object actual,
string message, params object[] parms);
See also...