@Test(timeout = TIMEOUT)
public void testMergeSort() {
DValue[] arrZero = new DValue[0];
Sorting.mergeSort(arrZero, new BasicComparator());
assertEquals(0, arrZero.length);
DValue[] arrOne = new DValue[1];
arrOne[0] = new DValue(4, 0);
Sorting.mergeSort(arrOne, new BasicComparator());
assertEquals(1, arrOne.length);
assertEquals(4, arrOne[0].val.intValue());
Random rand = new Random();
HashMap<Integer, Integer> values = new HashMap<Integer, Integer>();
for (int i = 0; i < 50; i++) {
int arrlen = rand.nextInt(1000) + 2;
DValue[] arrMany = new DValue[arrlen];
DValue[] arrManySorted = new DValue[arrlen];
for (int j = 0; j < arrlen; j++) {
arrMany[j] = new DValue(rand.nextInt(200) - 90, 0);
if (values.containsKey(arrMany[j].val)) {
arrMany[j].count = values.get(arrMany[j].val) + 1;
values.put(arrMany[j].val, arrMany[j].count);
} else {
values.put(arrMany[j].val, 0);
}
}
System.arraycopy(arrMany, 0, arrManySorted, 0, arrlen);
Arrays.sort(arrManySorted);
Sorting.mergeSort(arrMany, new BasicComparator());
assertArrayEquals(arrManySorted, arrMany);
for (int j = 0; j < arrMany.length - 1; j++) {
if (arrMany[j].val.equals(arrMany[j + 1].val)) {
assertTrue(arrMany[j].count < arrMany[j + 1].count);
}
}
}
}
