Add tests, remove main in ThreeSumProblem (#5781)

Author: Hardvan

DIRECTORY.md

@@ -1023,6 +1023,7 @@
             * [MirrorOfMatrixTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/MirrorOfMatrixTest.java)
             * [PalindromeSinglyLinkedListTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/PalindromeSinglyLinkedListTest.java)
             * [RangeInSortedArrayTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/RangeInSortedArrayTest.java)
+            * [ThreeSumProblemTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/ThreeSumProblemTest.java)
             * [TwoSumProblemTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/TwoSumProblemTest.java)
             * [WordBoggleTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/misc/WordBoggleTest.java)
           * others

src/main/java/com/thealgorithms/misc/ThreeSumProblem.java

@@ -7,29 +7,10 @@
 import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Scanner;
 import java.util.Set;
 
 public class ThreeSumProblem {
 
-    public static void main(String[] args) {
-        Scanner scan = new Scanner(System.in);
-        System.out.print("Enter the target sum ");
-        int ts = scan.nextInt();
-        System.out.print("Enter the number of elements in the array ");
-        int n = scan.nextInt();
-        System.out.println("Enter all your array elements:");
-        int[] arr = new int[n];
-        for (int i = 0; i < n; i++) {
-            arr[i] = scan.nextInt();
-        }
-        ThreeSumProblem th = new ThreeSumProblem();
-        System.out.println("Brute Force Approach\n" + (th.bruteForce(arr, ts)) + "\n");
-        System.out.println("Two Pointer Approach\n" + (th.twoPointer(arr, ts)) + "\n");
-        System.out.println("Hashmap Approach\n" + (th.hashMap(arr, ts)));
-        scan.close();
-    }
-
     public List<List<Integer>> bruteForce(int[] nums, int target) {
         List<List<Integer>> arr = new ArrayList<List<Integer>>();
 

src/test/java/com/thealgorithms/misc/ThreeSumProblemTest.java

@@ -0,0 +1,52 @@
+package com.thealgorithms.misc;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+public class ThreeSumProblemTest {
+
+    private ThreeSumProblem tsp;
+
+    @BeforeEach
+    public void setup() {
+        tsp = new ThreeSumProblem();
+    }
+
+    @ParameterizedTest
+    @MethodSource("bruteForceTestProvider")
+    public void testBruteForce(int[] nums, int target, List<List<Integer>> expected) {
+        assertEquals(expected, tsp.bruteForce(nums, target));
+    }
+
+    @ParameterizedTest
+    @MethodSource("twoPointerTestProvider")
+    public void testTwoPointer(int[] nums, int target, List<List<Integer>> expected) {
+        assertEquals(expected, tsp.twoPointer(nums, target));
+    }
+
+    @ParameterizedTest
+    @MethodSource("hashMapTestProvider")
+    public void testHashMap(int[] nums, int target, List<List<Integer>> expected) {
+        assertEquals(expected, tsp.hashMap(nums, target));
+    }
+
+    private static Stream<Arguments> bruteForceTestProvider() {
+        return Stream.of(Arguments.of(new int[] {1, 2, -3, 4, -2, -1}, 0, Arrays.asList(Arrays.asList(-3, 1, 2), Arrays.asList(-3, -1, 4))), Arguments.of(new int[] {1, 2, 3, 4, 5}, 50, new ArrayList<>()));
+    }
+
+    private static Stream<Arguments> twoPointerTestProvider() {
+        return Stream.of(Arguments.of(new int[] {0, -1, 2, -3, 1}, 0, Arrays.asList(Arrays.asList(-3, 1, 2), Arrays.asList(-1, 0, 1))), Arguments.of(new int[] {-5, -4, -3, -2, -1}, -10, Arrays.asList(Arrays.asList(-5, -4, -1), Arrays.asList(-5, -3, -2))));
+    }
+
+    private static Stream<Arguments> hashMapTestProvider() {
+        return Stream.of(Arguments.of(new int[] {1, 2, -1, -4, 3, 0}, 2, Arrays.asList(Arrays.asList(-1, 0, 3), Arrays.asList(-1, 1, 2))), Arguments.of(new int[] {5, 7, 9, 11}, 10, new ArrayList<>()), Arguments.of(new int[] {}, 0, new ArrayList<>()));
+    }
+}