@Test(dataProvider = "combinations")
public void allCombinations(final int n, final int k) {

	final Random random = new Random();
	final Set<String> subsets = new HashSet<>();
	for (int i = 0; i < 3000; ++i) {
		subsets.add(Arrays.toString(Combinatorics.subset(n, new int[k], random)));
	}
	Assert.assertEquals(subsets.size(), binomial(n, k));
}