void LineSegmentTest::testStraddles()
 {
     CPPUNIT_ASSERT(  s1.straddles(s2) ); //crossed lines
     CPPUNIT_ASSERT(  s4.straddles(s1) ); //end Point on other line
     CPPUNIT_ASSERT(  s3.straddles(s5) ); //lines on eachother
     CPPUNIT_ASSERT( !s1.straddles(s4) ); //other end Point on line
     CPPUNIT_ASSERT( !s1.straddles(s3) ); //same edge point
     CPPUNIT_ASSERT( !s3.straddles(s4) ); //no intersection
     CPPUNIT_ASSERT( !s1.straddles(s6) ); //intersecting AABB
 }