Add unit tests for the "Number of Employees Who Met the Target" problem.

src/main/java/com/leetcode/easy/NumberOfEmployeesWhoMetTheTarget2798.java

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+// Tags: Array
+package com.leetcode.easy;
+
+public class NumberOfEmployeesWhoMetTheTarget2798 {
+    /**
+     * Time Complexity: O(n) where n is the length of the hours array
+     * - We iterate through the entire array once
+     * - Each element is checked exactly once
+     * <p>
+     * Space Complexity: O(1)
+     * - Only uses a constant amount of extra space (variables res and hour)
+     * - No additional data structures are allocated
+     */
+    public int numberOfEmployeesWhoMetTarget(int[] hours, int target) {
+        int res = 0;
+        for (int hour : hours) {
+            if (hour >= target) {
+                res++;
+            }
+        }
+        return res;
+    }
+}

src/test/java/com/leetcode/easy/NumberOfEmployeesWhoMetTheTarget2798Test.java

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+package com.leetcode.easy;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class NumberOfEmployeesWhoMetTheTarget2798Test {
+    private NumberOfEmployeesWhoMetTheTarget2798 solution;
+
+    @BeforeEach
+    void setUp() {
+        solution = new NumberOfEmployeesWhoMetTheTarget2798();
+    }
+
+    @Test
+    void testNumberOfEmployeesWhoMetTarget_Example1() {
+        int[] hours = {0, 1, 2, 3, 4};
+        int target = 2;
+
+        int result = solution.numberOfEmployeesWhoMetTarget(hours, target);
+
+        assertEquals(3, result);
+    }
+
+    @Test
+    void testNumberOfEmployeesWhoMetTarget_Example2() {
+        int[] hours = {5, 1, 4, 2, 3};
+        int target = 6;
+
+        int result = solution.numberOfEmployeesWhoMetTarget(hours, target);
+
+        assertEquals(0, result);
+    }
+}