public void TestContainsSubject()
{
var c = new TripleCollection();
c.AddRange(new[] { T1, T2, T3, T4, T5, T6 });
Assert.IsTrue(c.ContainsSubject("http://example.org/s"));
Assert.IsTrue(c.ContainsSubject("http://example.org/s1"));
Assert.IsFalse(c.ContainsSubject("http://example.org/p"));
}