@Test
    public void testClosestLess() {
        int[][] points = {{1,2}};
        int[][] results = ClosestPoints.getTopN(points,3);
        assertEquals(results.length, 1);
    }

The expected:<3> but was:<1> error message is not informative at all.

How should cases where the amount of points wanted is more than the given? Just giving empty coords ({0,0}) doesn't work and this is not indicated in the description.