@Test
public void testGetClosestAtom_Double_Double_IAtomContainer_IAtom() {

    IAtom atom1 = new Atom("C");
    atom1.setPoint2d(new Point2d(1, 0));
    IAtom atom2 = new Atom("C");
    atom2.setPoint2d(new Point2d(5, 0));
    IAtomContainer acont = new AtomContainer();
    acont.addAtom(atom1);
    acont.addAtom(atom2);
    Assert.assertEquals(atom2, GeometryTools.getClosestAtom(1.0, 0.0, acont, atom1));
    Assert.assertEquals(atom1, GeometryTools.getClosestAtom(1.0, 0.0, acont, null));
}