Unit test for MergeSort

algorithms/src/test/java/com/baeldung/algorithms/mergesort/MergeSortTest.java

@@ -0,0 +1,25 @@
+package com.baeldung.algorithms.mergesort;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class MergeSortTest {
+
+    @Test
+    void positiveTest() {
+        int[] input = { 5, 1, 6, 2, 3, 4 };
+        int[] expected = { 1, 2, 3, 4, 5, 6 };
+        MergeSort.mergeSort(input, input.length);
+        assertArrayEquals(expected, input);
+    }
+
+    @Test
+    void negativeTest() {
+        int[] input = { 5, 1, 6, 2, 3, 4 };
+        int[] expected = { 1, 2, 3, 4, 6, 5 };
+        MergeSort.mergeSort(input, input.length);
+        assertArrayEquals(expected, input);
+    }
+
+}