Add Dual Pivot QuickSort (#3357)

src/test/java/com/thealgorithms/sorts/DualPivotQuickSortTest.java

@@ -0,0 +1,63 @@
+package com.thealgorithms.sorts;
+
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author Debasish Biswas (https://github.com/debasishbsws)
+ * @see DualPivotQuickSort
+ */
+class DualPivotQuickSortTest {
+
+    private DualPivotQuickSort dualPivotquickSort = new DualPivotQuickSort();
+
+    @Test
+    void quickSortEmptyArrayShouldPass() {
+        Integer[] array = {};
+        Integer[] sorted = dualPivotquickSort.sort(array);
+        Integer[] expected = {};
+        assertArrayEquals(expected, sorted);
+    }
+
+    @Test
+    void quickSortSingleValueArrayShouldPass() {
+        Integer[] array = { 7 };
+        Integer[] sorted = dualPivotquickSort.sort(array);
+        Integer[] expected = { 7 };
+        assertArrayEquals(expected, sorted);
+    }
+
+    @Test
+    void quickSortWithIntegerArrayShouldPass() {
+        Integer[] array = { 49, 4, 36, 9, 144, 1 };
+        Integer[] sorted = dualPivotquickSort.sort(array);
+        Integer[] expected = { 1, 4, 9, 36, 49, 144 };
+        assertArrayEquals(expected, sorted);
+    }
+
+    @Test
+    void quickSortForArrayWithNegativeValuesShouldPass() {
+        Integer[] array = { 49, -36, -124, -49, 12, 9 };
+        Integer[] sorted = dualPivotquickSort.sort(array);
+        Integer[] expected = { -124, -49, -36, 9, 12, 49 };
+        assertArrayEquals(expected, sorted);
+    }
+
+    @Test
+    void quickSortForArrayWithDuplicateValuesShouldPass() {
+        Integer[] array = { 36, 1, 49, 1, 4, 9 };
+        Integer[] sorted = dualPivotquickSort.sort(array);
+        Integer[] expected = { 1, 1, 4, 9, 36, 49 };
+        assertArrayEquals(expected, sorted);
+    }
+
+    @Test
+    void quickSortWithStringArrayShouldPass() {
+        String[] array = { "cat", "ant", "eat", "boss", "dog", "apple" };
+        String[] sorted = dualPivotquickSort.sort(array);
+        String[] expected = { "ant", "apple", "boss", "cat", "dog", "eat" };
+        assertArrayEquals(expected, sorted);
+    }
+
+}