@Test
public void testReservoirSamplerSampledSize2() {

	RandomSampler<Double> sampler = new ReservoirSamplerWithoutReplacement<Double>(20000);
	Iterator<Double> sampled = sampler.sample(source.iterator());
	assertTrue("ReservoirSamplerWithoutReplacement sampled output size should not beyond the source size.", getSize(sampled) == SOURCE_SIZE);
}