Java/src/test/java/com/thealgorithms/backtracking/CombinationTest.java at master · TheAlgorithms/Java · GitHub

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packagecom.thealgorithms.backtracking;

importstaticorg.junit.jupiter.api.Assertions.assertEquals;
importstaticorg.junit.jupiter.api.Assertions.assertNotNull;
importstaticorg.junit.jupiter.api.Assertions.assertThrows;
importstaticorg.junit.jupiter.api.Assertions.assertTrue;

importjava.util.List;
importjava.util.Set;
importjava.util.TreeSet;
importorg.junit.jupiter.api.Test;

publicclassCombinationTest {

@Test
voidtestNegativeElement() {
Integer[] array = {1, 2};
assertThrows(IllegalArgumentException.class, () -> { Combination.combination(array, -1); });
 }

@Test
voidtestNoElement() {
List<TreeSet<Integer>> result = Combination.combination(newInteger[] {1, 2}, 0);
assertNotNull(result);
assertEquals(0, result.size());
 }

@Test
voidtestLengthOne() {
List<TreeSet<Integer>> result = Combination.combination(newInteger[] {1, 2}, 1);
assertEquals(1, result.get(0).iterator().next());
assertEquals(2, result.get(1).iterator().next());
 }

@Test
voidtestLengthTwo() {
List<TreeSet<Integer>> result = Combination.combination(newInteger[] {1, 2}, 2);
Integer[] arr = result.get(0).toArray(newInteger[2]);
assertEquals(1, arr[0]);
assertEquals(2, arr[1]);
 }

@Test
voidtestCombinationsWithStrings() {
List<TreeSet<String>> result = Combination.combination(newString[] {"a", "b", "c"}, 2);
assertEquals(3, result.size());
assertTrue(result.contains(newTreeSet<>(Set.of("a", "b"))));
assertTrue(result.contains(newTreeSet<>(Set.of("a", "c"))));
assertTrue(result.contains(newTreeSet<>(Set.of("b", "c"))));
 }
}