Add tests for SearchInsertPosition file

src/main/java/com/leetcode/arrays/binarysearch/SearchInsertPosition.java

@@ -1,3 +1,4 @@
+
 package com.leetcode.arrays.binarysearch;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
@@ -42,10 +43,14 @@ public class SearchInsertPosition {
      * @return
      */
     public static int searchInsert(int[] nums, int target) {
+    	if (nums == null) {
+            throw new IllegalArgumentException("nums must not be null");
+        }
+
         int low = 0;
         int high = nums.length - 1;
         while (low <= high) {
-            int mid = low + (high - low) / 2;
+        	int mid = low + ((high - low) >>> 1);
             if (nums[mid] == target) {
                 return mid;
             } else if (nums[mid] < target) {

src/test/java/com/leetcode/arrays/binarysearch/SearchInsertPositionTest.java

@@ -0,0 +1,48 @@
+package com.leetcode.arrays.binarysearch;
+
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+import com.leetcode.arrays.binarysearch.SearchInsertPosition;
+
+/**
+ * Unit tests for SearchInsertPosition.
+ */
+class SearchInsertPositionTest {
+
+    @Test
+    void test_targetFound() {
+        int[] nums = {1, 3, 5, 6};
+        assertEquals(2, SearchInsertPosition.searchInsert(nums, 5));
+    }
+
+    @Test
+    void test_targetSmallerThanAll() {
+        int[] nums = {10, 20, 30, 40};
+        assertEquals(0, SearchInsertPosition.searchInsert(nums, 5));
+    }
+
+    @Test
+    void test_targetGreaterThanAll() {
+        int[] nums = {10, 20, 30, 40};
+        assertEquals(4, SearchInsertPosition.searchInsert(nums, 50));
+    }
+
+    @Test
+    void test_targetBetweenTwoElements() {
+        int[] nums = {1, 3, 5, 6};
+        assertEquals(1, SearchInsertPosition.searchInsert(nums, 2));
+    }
+
+    @Test
+    void test_emptyArray() {
+        int[] nums = {};
+        assertEquals(0, SearchInsertPosition.searchInsert(nums, 7));
+    }
+
+    @Test
+    void test_nullArray_throwsException() {
+        int[] nums = null;
+        assertThrows(IllegalArgumentException.class,
+                () -> SearchInsertPosition.searchInsert(nums, 1));
+    }
+}