public function testClusterContains()
{
$point1 = new Point(1, 1);
$point2 = new Point(1, 1);
$cluster = new Cluster();
$cluster[] = $point1;
$this->assertTrue($cluster->contains($point1));
$this->assertFalse($cluster->contains($point2));
$cluster[] = $point2;
$this->assertTrue($cluster->contains($point1));
$this->assertTrue($cluster->contains($point2));
}